Li Zhang; Changjiu Sun; Tingwei He; Yuanzhi Jiang; Junli Wei; Yanmin Huang; Mingjian Yuan; Li Zhang; Changjiu Sun; Tingwei He; Yuanzhi Jiang; Junli Wei; Yanmin Huang; Mingjian Yuan

doi:10.1038/s41377-021-00501-0

[1]	Okumura, H., Misawa, S. & Yoshida, S. Epitaxial growth of cubic and hexagonal GaN on GaAs by gas-source molecular-beam epitaxy. Appl. Phys. Lett. 59, 1058–1060 (1991). doi: 10.1063/1.106344
[2]	Duffy, M. T. et al. Epitaxial growth and piezoelectric properties of A1N, GaN, and GaAs on sapphire or spinel. J. Electron. Mater. 2, 359–372 (1973). doi: 10.1007/BF02666163
[3]	Wu, T. L. et al. Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off. Nat. Photonics 12, 235–240 (2018). doi: 10.1038/s41566-018-0112-9
[4]	Baldo, M. A. et al. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395, 151–154 (1998). doi: 10.1038/25954
[5]	Dai, X. L. et al. Solution-processed, high-performance light-emitting diodes based on quantum dots. Nature 515, 96–99 (2014). doi: 10.1038/nature13829
[6]	Quan, L. N. et al. Perovskites for next-generation optical sources. Chem. Rev. 119, 7444–7477 (2019). doi: 10.1021/acs.chemrev.9b00107
[7]	He, T. W. et al. Structured perovskite light absorbers for efficient and stable photovoltaics. Adv. Mater. 32, 1903937 (2020). doi: 10.1002/adma.201903937
[8]	He, T. W. et al. Reduced-dimensional perovskite photovoltaics with homogeneous energy landscape. Nat. Commun. 11, 1672 (2020). doi: 10.1038/s41467-020-15451-1
[9]	Wang, L. et al. A chiral reduced-dimension perovskite for an efficient flexible circularly polarized light photodetector. Angew. Chem. Int. Ed. 59, 6442–6450 (2020). doi: 10.1002/anie.201915912
[10]	Huang, Y. M. et al. A-site cation engineering for highly efficient MAPbI₃ single-crystal X-ray detector. Angew. Chem. Int. Ed. 58, 17834–17842 (2019). doi: 10.1002/anie.201911281
[11]	Tan, Z. K. et al. Bright light-emitting diodes based on organometal halide perovskite. Nat. Nanotechnol. 9, 687–692 (2014). doi: 10.1038/nnano.2014.149
[12]	Xu, W. D. et al. Rational molecular passivation for high-performance perovskite light-emitting diodes. Nat. Photonics 13, 418–424 (2019). doi: 10.1038/s41566-019-0390-x
[13]	Zhao, X. F. et al. Opportunities and challenges in perovskite light-emitting devices. ACS Photonics 5, 3866–3875 (2018). doi: 10.1021/acsphotonics.8b00745
[14]	Li, G. R. et al. Efficient light-emitting diodes based on nanocrystalline perovskite in a dielectric polymer matrix. Nano Lett. 15, 2640–2644 (2015). doi: 10.1021/acs.nanolett.5b00235
[15]	Chiba, T. et al. Anion-exchange red perovskite quantum dots with ammonium iodine salts for highly efficient light-emitting devices. Nat. Photonics 12, 681–687 (2018). doi: 10.1038/s41566-018-0260-y
[16]	Zhao, B. D. et al. High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes. Nat. Photonics 12, 783–789 (2018). doi: 10.1038/s41566-018-0283-4
[17]	Cao, Y. et al. Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures. Nature 562, 249–253 (2018). doi: 10.1038/s41586-018-0576-2
[18]	Lin, K. B. et al. Perovskite light-emitting diodes with external quantum efficiency exceeding 20 per cent. Nature 562, 245–248 (2018). doi: 10.1038/s41586-018-0575-3
[19]	Yong, Z. J. et al. Doping-Enhanced short-range order of perovskite nanocrystals for near-unity violet luminescence quantum yield. J. Am. Chem. Soc. 140, 9942–9951 (2018). doi: 10.1021/jacs.8b04763
[20]	Koscher, B. A. et al. Essentially trap-free CsPbBr₃ colloidal nanocrystals by postsynthetic thiocyanate surface treatment. J. Am. Chem. Soc. 139, 6566–6569 (2017). doi: 10.1021/jacs.7b02817
[21]	Shan, Q. S. et al. High performance metal halide perovskite light-emitting diode: from material design to device optimization. Small 13, 1701770 (2017). doi: 10.1002/smll.201701770
[22]	Kim, Y. H. et al. Comprehensive defect suppression in perovskite nanocrystals for high-efficiency light-emitting diodes. Nat. Photonics https://doi.org/10.1038/s41566-020-00732-4">https://doi.org/10.1038/s41566-020-00732-4 (2021).
[23]	Bao, C. X. et al. Bidirectional optical signal transmission between two identical devices using perovskite diodes. Nat. Electron. 3, 156–164 (2020). doi: 10.1038/s41928-020-0382-3
[24]	Luo, J. J. et al. Efficient and stable emission of warm-white light from lead-free halide double perovskites. Nature 563, 541–545 (2018). doi: 10.1038/s41586-018-0691-0
[25]	Cheng, L. et al. Multiple-quantum-well perovskites for high-performance light-emitting diodes. Adv. Mater. 32, 1904163 (2020). doi: 10.1002/adma.201904163
[26]	Jiang, Y. Z. et al. Reduced-dimensional α-CsPbX₃ perovskites for efficient and stable photovoltaics. Joule 2, 1356–1368 (2018). doi: 10.1016/j.joule.2018.05.004
[27]	Calabrese, J. et al. Preparation and characterization of layered lead halide compounds. J. Am. Chem. Soc. 113, 2328–2330 (1991). doi: 10.1021/ja00006a076
[28]	Mitzi, D. B. et al. Conducting tin halides with a layered organic-based perovskite structure. Nature 369, 467–469 (1994). doi: 10.1038/369467a0
[29]	Miao, Y. F. et al. Microcavity top-emission perovskite light-emitting diodes. Light. Sci. Appl. 9, 89 (2020). doi: 10.1038/s41377-020-0328-6
[30]	Yuan, M. J. et al. Perovskite energy funnels for efficient light-emitting diodes. Nat. Nanotechnol. 11, 872–877 (2016). doi: 10.1038/nnano.2016.110
[31]	Kim, Y. H. et al. Multicolored organic/inorganic hybrid perovskite light-emitting diodes. Adv. Mater. 27, 1248–1254 (2015). doi: 10.1002/adma.201403751
[32]	Wang, J. P. et al. Interfacial control toward efficient and low-voltage perovskite light-emitting diodes. Adv. Mater. 27, 2311–2316 (2015). doi: 10.1002/adma.201405217
[33]	Zhang, F. J. et al. Efficient blue perovskite light-emitting diodes boosted by 2D/3D energy cascade channels. Adv. Funct. Mater. 30, 2001732 (2020). doi: 10.1002/adfm.202001732
[34]	Hong, X., Ishihara, T. & Nurmikko, A. V. Photoconductivity and electroluminescence in lead iodide based natural quantum well structures. Solid State Commun. 84, 657–661 (1992). doi: 10.1016/0038-1098(92)90210-Z
[35]	Era, M. et al. Organic-inorganic heterostructure electroluminescent device using a layered perovskite semiconductor (C₆H₅C₂H₄NH₃)₂PbI₄. Appl. Phys. Lett. 65, 676–678 (1994). doi: 10.1063/1.112265
[36]	Kumagai, M. & Takagahara, T. Excitonic and nonlinear-optical properties of dielectric quantum-well structures. Phys. Rev. B 40, 12359 (1989). doi: 10.1103/PhysRevB.40.12359
[37]	Tanaka, K. et al. Image charge effect on two-dimensional excitons in an inorganic-organic quantum-well crystal. Phys. Rev. B 71, 045312 (2005). doi: 10.1103/PhysRevB.71.045312
[38]	Zhang, S. T. et al. Efficient red perovskite light-emitting diodes based on solution-processed multiple quantum wells. Adv. Mater. 29, 1606600 (2017). doi: 10.1002/adma.201606600
[39]	Traore, B. et al. Composite nature of layered hybrid perovskites: assessment on quantum and dielectric confinements and band alignment. ACS Nano 12, 3321–3332 (2018). doi: 10.1021/acsnano.7b08202
[40]	Katan, C., Mercier, N. & Even, J. Quantum and dielectric confinement effects in lower-dimensional hybrid perovskite semiconductors. Chem. Rev. 119, 3140–3192 (2019). doi: 10.1021/acs.chemrev.8b00417
[41]	Quan, L. N. et al. Ligand-stabilized reduced-dimensionality perovskites. J. Am. Chem. Soc. 138, 2649–2655 (2016). doi: 10.1021/jacs.5b11740
[42]	Wang, N. N. et al. Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells. Nat. Photonics 10, 699–704 (2016). doi: 10.1038/nphoton.2016.185
[43]	Wu, C. et al. Alternative type two-dimensional-three-dimensional lead halide perovskite with inorganic sodium ions as a spacer for high-performance light-emitting diodes. ACS Nano 13, 1645–1654 (2019).
[44]	He, Z. F. et al. High-efficiency red light-emitting diodes based on multiple quantum wells of phenylbutylammonium-cesium lead iodide perovskites. ACS Photonics 6, 587–594 (2019). doi: 10.1021/acsphotonics.8b01435
[45]	Chu, Z. M. et al. Large cation ethylammonium incorporated perovskite for efficient and spectra stable blue light-emitting diodes. Nat. Commun. 11, 4165 (2020). doi: 10.1038/s41467-020-17943-6
[46]	Mitzi, D. B. et al. Conducting layered organic-inorganic halides containing < 110 > -oriented perovskite sheets. Science 267, 1473–1476 (1995). doi: 10.1126/science.267.5203.1473
[47]	Mitzi, D. B. In Progress in Inorganic Chemistry (ed. Karlin, K. D. ) 1–121 (1999).
[48]	Liang, H. Y. et al. High color purity lead-free perovskite light-emitting diodes via Sn stabilization. Adv. Sci. 7, 1903213 (2020). doi: 10.1002/advs.201903213
[49]	Sichert, J. A. et al. Quantum size effect in organometal halide perovskite nanoplatelets. Nano Lett. 15, 6521–6527 (2015). doi: 10.1021/acs.nanolett.5b02985
[50]	Ortiz-Cervantes, C., Carmona-Monroy, P. & Solis-Ibarra, D. Two-dimensional halide perovskites in solar cells: 2D or not 2D? ChemSusChem 12, 1560–1575 (2019). doi: 10.1002/cssc.201802992
[51]	Quan, L. N. et al. Perovskites for light emission. Adv. Mater. 30, 1801996 (2018). doi: 10.1002/adma.201801996
[52]	Ishihara, T., Takahashi, J. & Goto, T. Exciton state in two-dimensional perovskite semiconductor (C₁₀H₂₁NH₃)₂PbI₄. Solid State Commun. 69, 933–936 (1989). doi: 10.1016/0038-1098(89)90935-6
[53]	Ishihara, T., Takahashi, J. & Goto, T. Optical properties due to electronic transitions in two-dimensional semiconductors (C_nH_2n+1NH₃)₂PbI₄. Phys. Rev. B 42, 11099 (1990). doi: 10.1103/PhysRevB.42.11099
[54]	Stoumpos, C. C. et al. High members of the 2D Ruddlesden-Popper halide perovskites: synthesis, optical properties, and solar cells of (CH₃(CH₂)₃NH₃)₂(CH₃NH₃)₄Pb₅I₁₆. Chem 2, 427–440 (2017). doi: 10.1016/j.chempr.2017.02.004
[55]	Gan, L. et al. Effects of organic cation length on exciton recombination in two-dimensional layered lead iodide hybrid perovskite crystals. J. Phys. Chem. Lett. 8, 5177–5183 (2017). doi: 10.1021/acs.jpclett.7b02083
[56]	Ni, L. M. et al. Real-time observation of exciton-phonon coupling dynamics in self-assembled hybrid perovskite quantum wells. ACS Nano 11, 10834–10843 (2017). doi: 10.1021/acsnano.7b03984
[57]	Soe, C. M. M. et al. Structural and thermodynamic limits of layer thickness in 2D halide perovskites. Proc. Natl Acad. Sci. USA 116, 58–66 (2019). doi: 10.1073/pnas.1811006115
[58]	Yaffe, O. et al. Excitons in ultrathin organic-inorganic perovskite crystals. Phys. Rev. B 92, 045414 (2015). doi: 10.1103/PhysRevB.92.045414
[59]	Feldmann, S. et al. Photodoping through local charge carrier accumulation in alloyed hybrid perovskites for highly efficient luminescence. Nat. Photonics 14, 123–128 (2020). doi: 10.1038/s41566-019-0546-8
[60]	Chen, X. H. et al. Impact of layer thickness on the charge carrier and spin coherence lifetime in two-dimensional layered perovskite single crystals. ACS Energy Lett. 3, 2273–2279 (2018). doi: 10.1021/acsenergylett.8b01315
[61]	Delport, G. et al. Exciton-exciton annihilation in two-dimensional halide perovskites at room temperature. J. Phys. Chem. Lett. 10, 5153–5159 (2019). doi: 10.1021/acs.jpclett.9b01595
[62]	Xing, G. C. et al. Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence. Nat. Commun. 8, 14558 (2017). doi: 10.1038/ncomms14558
[63]	Byun, J. et al. Efficient visible quasi-2D perovskite light-emitting diodes. Adv. Mater. 28, 7515–7520 (2016). doi: 10.1002/adma.201601369
[64]	Quintero-Bermudez, R. et al. Compositional and orientational control in metal halide perovskites of reduced dimensionality. Nat. Mater. 17, 900–907 (2018). doi: 10.1038/s41563-018-0154-x
[65]	Jeon, N. J. et al. Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells. Nat. Mater. 13, 897–903 (2014). doi: 10.1038/nmat4014
[66]	Soe, C. M. M. et al. Understanding film formation morphology and orientation in high member 2D Ruddlesden-Popper perovskites for high‐efficiency solar cells. Adv. Energy Mater. 8, 1700979 (2018). doi: 10.1002/aenm.201700979
[67]	Zhang, X. et al. Phase transition control for high performance Ruddlesden-Popper perovskite solar cells. Adv. Mater. 30, 1707166 (2018). doi: 10.1002/adma.201707166
[68]	Venkatesan, N. R., Labram, J. G. & Chabinyc, M. L. Charge-carrier dynamics and crystalline texture of layered Ruddlesden-Popper hybrid lead iodide perovskite thin films. ACS Energy Lett. 3, 380–386 (2018). doi: 10.1021/acsenergylett.7b01245
[69]	Yu, J. C. et al. Improving the stability and performance of perovskite light-emitting diodes by thermal annealing treatment. Adv. Mater. 28, 6906–6913 (2016). doi: 10.1002/adma.201601105
[70]	Hamill, J. C. Jr., Schwartz, J. & Loo, Y. L. Influence of solvent coordination on hybrid organic-inorganic perovskite formation. ACS Energy Lett. 3, 92–97 (2018). doi: 10.1021/acsenergylett.7b01057
[71]	Zhao, L. F. et al. In situ preparation of metal halide perovskite nanocrystal thin films for improved light-emitting devices. ACS Nano 11, 3957–3964 (2017). doi: 10.1021/acsnano.7b00404
[72]	Xiao, Z. G. et al. Engineering perovskite nanocrystal surface termination for light-emitting diodes with external quantum efficiency exceeding 15%. Adv. Funct. Mater. 29, 1807284 (2019). doi: 10.1002/adfm.201807284
[73]	Xiao, Z. G. et al. Efficient perovskite light-emitting diodes featuring nanometre-sized crystallites. Nat. Photonics 11, 108–115 (2017). doi: 10.1038/nphoton.2016.269
[74]	Soe, C. M. M. et al. New type of 2D perovskites with alternating cations in the interlayer space, (C(NH₂)₃)(CH₃NH₃)_nPb_nI_3n+1: structure, properties, and photovoltaic performance. J. Am. Chem. Soc. 139, 16297–16309 (2017). doi: 10.1021/jacs.7b09096
[75]	Quan, L. N. et al. Tailoring the energy landscape in quasi-2D halide perovskites enables efficient green-light emission. Nano Lett. 17, 3701–3709 (2017). doi: 10.1021/acs.nanolett.7b00976
[76]	Yantara, N. et al. Designing efficient energy funneling kinetics in Ruddlesden-popper perovskites for high-performance light-emitting diodes. Adv. Mater. 30, 1800818 (2018). doi: 10.1002/adma.201800818
[77]	Lei, L. et al. Efficient energy funneling in quasi-2D perovskites: from light emission to lasing. Adv. Mater. 32, 1906571 (2020). doi: 10.1002/adma.201906571
[78]	Ban, M. Y. et al. Solution-processed perovskite light emitting diodes with efficiency exceeding 15% through additive-controlled nanostructure tailoring. Nat. Commun. 9, 3892 (2018). doi: 10.1038/s41467-018-06425-5
[79]	Quan, L. N. et al. Edge stabilization in reduced-dimensional perovskites. Nat. Commun. 11, 170 (2020). doi: 10.1038/s41467-019-13944-2
[80]	Gao, C. C. et al. Multifunctional naphthol sulfonic salt incorporated in lead-free 2D tin halide perovskite for red light-emitting diodes. ACS Photonics 7, 1915–1922 (2020). doi: 10.1021/acsphotonics.0c00497
[81]	Yang, X. L. et al. Efficient green light-emitting diodes based on quasi-two-dimensional composition and phase engineered perovskite with surface passivation. Nat. Commun. 9, 570 (2018). doi: 10.1038/s41467-018-02978-7
[82]	Lee, S. et al. Control of interface defects for efficient and stable quasi-2D Perovskite light-emitting diodes using nickel oxide hole injection layer. Adv. Sci. 5, 1801350 (2018). doi: 10.1002/advs.201801350
[83]	Wang, Z. B. et al. Manipulating the trade-off between quantum yield and electrical conductivity for high-brightness quasi-2D perovskite light-emitting diodes. Adv. Funct. Mater. 28, 1804187 (2018). doi: 10.1002/adfm.201804187
[84]	Tian, Y. et al. Highly efficient spectrally stable red perovskite light‐emitting diodes. Adv. Mater. 30, 1707093 (2018). doi: 10.1002/adma.201707093
[85]	Meng, F. Y. et al. Co-interlayer engineering toward efficient green quasi-two-dimensional perovskite light-emitting diodes. Adv. Funct. Mater. 30, 1910167 (2020). doi: 10.1002/adfm.201910167
[86]	Cheng, T. et al. Stoichiometry control for the tuning of grain passivation and domain distribution in green quasi-2D metal halide perovskite films and light-emitting diodes. Adv. Funct. Mater. 30, 2001816 (2020). doi: 10.1002/adfm.202001816
[87]	Series, B. T. Parameter Values for Ultra-high Definition Television Systems for Production and International Programme Exchange (2012).
[88]	Kumar, S. et al. Efficient blue electroluminescence using quantum-confined two-dimensional perovskites. ACS Nano 10, 9720–9729 (2016). doi: 10.1021/acsnano.6b05775
[89]	Wang, Q. et al. Efficient sky-blue perovskite light-emitting devices based on ethylammonium bromide induced layered perovskites. ACS Appl. Mater. Interfaces 9, 29901–29906 (2017). doi: 10.1021/acsami.7b07458
[90]	Cheng, L. et al. Sky-blue perovskite light-emitting diodes based on quasi-two-dimensional layered perovskites. Chin. Chem. Lett. 28, 29–31 (2017). doi: 10.1016/j.cclet.2016.07.001
[91]	Chen, H. T. et al. Sodium ion modifying in situ fabricated CsPbBr₃ nanoparticles for efficient perovskite light emitting diodes. Adv. Optic. Mater. 7, 1900747 (2019). doi: 10.1002/adom.201900747
[92]	Chen, P. et al. Charge-transfer versus energy-transfer in quasi-2D perovskite light emitting diodes. Nano energy 50, 615–622 (2018). doi: 10.1016/j.nanoen.2018.06.008
[93]	Protesescu, L. et al. Nanocrystals of cesium lead halide perovskites (CsPbX₃, X= Cl, Br, and I): novel optoelectronic materials showing bright emission with wide color gamut. Nano Lett. 15, 3692–3696 (2015). doi: 10.1021/nl5048779
[94]	Song, J. Z. et al. Quantum dot light-emitting diodes based on inorganic perovskite cesium lead halides (CsPbX₃). Adv. Mater. 27, 7162–7167 (2015). doi: 10.1002/adma.201502567
[95]	Li, G. R. et al. Highly efficient perovskite nanocrystal light-emitting diodes enabled by a universal crosslinking method. Adv. Mater. 28, 3528–3534 (2016). doi: 10.1002/adma.201600064
[96]	Dutta, A. et al. Near-Unity photoluminescence quantum efficiency for all CsPbX₃ (X= Cl, Br, and I) perovskite nanocrystals: a generic synthesis approach. Angew. Chem. Int. Ed. 58, 5552–5556 (2019). doi: 10.1002/anie.201900374
[97]	Li, Z. C. et al. Modulation of recombination zone position for quasi-two-dimensional blue perovskite light-emitting diodes with efficiency exceeding 5%. Nat. Commun. 10, 1027 (2019). doi: 10.1038/s41467-019-09011-5
[98]	Vashishtha, P. et al. High efficiency blue and green light-emitting diodes using Ruddlesden-Popper inorganic mixed halide perovskites with butylammonium interlayers. Chem. Mater. 31, 83–89 (2019). doi: 10.1021/acs.chemmater.8b02999
[99]	Yao, E. P. et al. High-brightness blue and white leds based on inorganic perovskite nanocrystals and their composites. Adv. Mater. 29, 1606859 (2017). doi: 10.1002/adma.201606859
[100]	Vashishtha, P. & Halpert, J. E. Field-driven ion migration and color instability in red-emitting mixed halide perovskite nanocrystal light-emitting diodes. Chem. Mater. 29, 5965–5973 (2017). doi: 10.1021/acs.chemmater.7b01609
[101]	Brivio, F., Caetano, C. & Walsh, A. Thermodynamic origin of photoinstability in the CH₃NH₃Pb(I_1-xBr_x)₃ hybrid halide perovskite alloy. J. Phys. Chem. Lett. 7, 1083–1087 (2016). doi: 10.1021/acs.jpclett.6b00226
[102]	Wang, Q. et al. Efficient sky-blue perovskite light-emitting diodes via photoluminescence enhancement. Nat. Commun. 10, 5633 (2019). doi: 10.1038/s41467-019-13580-w
[103]	Yuan, Y. B. & Huang, J. S. Ion migration in organometal trihalide perovskite and its impact on photovoltaic efficiency and stability. Acc. Chem. Res. 49, 286–293 (2016). doi: 10.1021/acs.accounts.5b00420
[104]	Ma, D. X. et al. Chloride insertion-immobilization enables bright, narrowband, and stable blue-emitting perovskite diodes. J. Am. Chem. Soc. 142, 5126–5134 (2020). doi: 10.1021/jacs.9b12323
[105]	Zhao, J. J. et al. Strained hybrid perovskite thin films and their impact on the intrinsic stability of perovskite solar cells. Sci. Adv. 3, eaao5616 (2017). doi: 10.1126/sciadv.aao5616
[106]	Kubicki, D. J. et al. Cation dynamics in mixed-cation (MA)_x(FA)_1-xPbI₃ hybrid perovskites from solid-state NMR. J. Am. Chem. Soc. 139, 10055–10061 (2017). doi: 10.1021/jacs.7b04930
[107]	Philippe, B. et al. Chemical distribution of multiple cation (Rb⁺, Cs⁺, MA⁺, and FA⁺) perovskite materials by photoelectron spectroscopy. Chem. Mater. 29, 3589–3596 (2017). doi: 10.1021/acs.chemmater.7b00126
[108]	Gao, L. L. et al. Improved environmental stability and solar cell efficiency of (MA, FA) PbI₃ perovskite using a wide-band-gap 1D thiazolium lead iodide capping layer strategy. ACS Energy Lett. 4, 1763–1769 (2019). doi: 10.1021/acsenergylett.9b00930
[109]	Linaburg, M. R. et al. Cs_1-xRb_xPbCl₃ and Cs_1-xRb_xPbBr₃ solid solutions: understanding octahedral tilting in lead halide perovskites. Chem. Mater. 29, 3507–3514 (2017). doi: 10.1021/acs.chemmater.6b05372
[110]	Jiang, Y. Z. et al. Spectra stable blue perovskite light-emitting diodes. Nat. Commun. 10, 1868 (2019). doi: 10.1038/s41467-019-09794-7
[111]	Lanzetta, L. et al. Two-dimensional organic tin halide perovskites with tunable visible emission and their use in light-emitting devices. ACS Energy Lett. 2, 1662–1668 (2017). doi: 10.1021/acsenergylett.7b00414
[112]	Yuan, F. L. et al. Color-pure red light-emitting diodes based on two-dimensional lead-free perovskites. Sci. Adv. 6, eabb0253 (2020). doi: 10.1126/sciadv.abb0253
[113]	Gauthron, K. et al. Optical spectroscopy of two-dimensional layered (C₆H₅C₂H₄-NH₃)₂-PbI₄ perovskite. Opt. Express 18, 5912–5919 (2010). doi: 10.1364/OE.18.005912
[114]	Gong, X. W. et al. Electron-phonon interaction in efficient perovskite blue emitters. Nat. Mater. 17, 550–556 (2018). doi: 10.1038/s41563-018-0081-x
[115]	Yantara, N. et al. Designing the perovskite structural landscape for efficient blue emission. ACS Energy Lett. 5, 1593–1600 (2020). doi: 10.1021/acsenergylett.0c00559
[116]	Jin, Y. et al. Synergistic effect of dual ligands on stable blue quasi-2D perovskite light-emitting diodes. Adv. Funct. Mater. 30, 1908339 (2020). doi: 10.1002/adfm.201908339
[117]	Yuan, S. et al. Optimization of low-dimensional components of quasi-2D perovskite films for deep-blue light-emitting diodes. Adv. Mater. 31, 1904319 (2019). doi: 10.1002/adma.201904319
[118]	Leung, T. L. et al. Mixed spacer cation stabilization of blue-emitting n = 2 Ruddlesden-Popper organic-inorganic halide perovskite films. Adv. Optic. Mater. 8, 1901679 (2020). doi: 10.1002/adom.201901679
[119]	Chang, J. et al. Enhanced performance of red perovskite light-emitting diodes through the dimensional tailoring of perovskite multiple quantum wells. J. Phys. Chem. Lett. 9, 881–886 (2018). doi: 10.1021/acs.jpclett.7b03417
[120]	Ren, Z. W. et al. High-performance blue perovskite light-emitting diodes enabled by efficient energy transfer between coupled quasi-2D perovskite layers. Adv. Mater. 33, 2005570 (2021). doi: 10.1002/adma.202005570
[121]	Xing, J. et al. Color-stable highly luminescent sky-blue perovskite light-emitting diodes. Nat. Commun. 9, 3541 (2018). doi: 10.1038/s41467-018-05909-8
[122]	Wang, Y. K. et al. Chelating-agent-assisted control of CsPbBr₃ quantum well growth enables stable blue perovskite emitters. Nat. Commun. 11, 3674 (2020). doi: 10.1038/s41467-020-17482-0
[123]	Yang, Z. Y. et al. Low-dimensionality perovskites yield high electroluminescence. Sci. Bull. 65, 1057–1060 (2020). doi: 10.1016/j.scib.2020.03.015
[124]	Lee, S. J. et al. Versatile defect passivation methods for metal halide perovskite materials and their application to light-emitting devices. Adv. Mater. 31, 1805244 (2019). doi: 10.1002/adma.201805244
[125]	Shen, H. B. et al. Visible quantum dot light-emitting diodes with simultaneous high brightness and efficiency. Nat. Photonics 13, 192–197 (2019). doi: 10.1038/s41566-019-0364-z
[126]	Chen, Y. N. et al. 2D Ruddlesden-Popper perovskites for optoelectronics. Adv. Mater. 30, 1703487 (2018). doi: 10.1002/adma.201703487
[127]	Yu, J. C. et al. Effect of perovskite film morphology on device performance of perovskite light-emitting diodes. Nanoscale 11, 1505–1514 (2019). doi: 10.1039/C8NR08683D
[128]	Kim, Y. H., Kim, J. S. & Lee, T. W. Strategies to improve luminescence efficiency of metal-halide perovskites and light-emitting diodes. Adv. Mater. 31, 1804595 (2019). doi: 10.1002/adma.201804595
[129]	Sum, T. C., Righetto, M. & Lim, S. S. Quo vadis, perovskite emitters? J. Chem. Phys. 152, 130901 (2020). doi: 10.1063/1.5132366
[130]	Liu, X. K. & Gao, F. Organic-inorganic hybrid Ruddlesden-Popper perovskites: an emerging paradigm for high-performance light-emitting diodes. J. Phys. Chem. Lett. 9, 2251–2258 (2018). doi: 10.1021/acs.jpclett.8b00755
[131]	Chin, X. Y. et al. Self-assembled hierarchical nanostructured perovskites enable highly efficient LEDs via an energy cascade. Energy Environ. Sci. 11, 1770–1778 (2018). doi: 10.1039/C8EE00293B
[132]	Gao, L. et al. Efficient near-infrared light-emitting diodes based on quantum dots in layered perovskite. Nat. Photonics 14, 227–233 (2020). doi: 10.1038/s41566-019-0577-1
[133]	Yang, X. L. et al. Effects of organic cations on the structure and performance of quasi-two-dimensional perovskite-based light-emitting diodes. J. Phys. Chem. Lett. 10, 2892–2897 (2019). doi: 10.1021/acs.jpclett.9b00910
[134]	Qin, C. J. et al. Triplet management for efficient perovskite light-emitting diodes. Nat. Photonics 14, 70–75 (2020). doi: 10.1038/s41566-019-0545-9
[135]	Han, D. B. et al. Efficient light-emitting diodes based on in situ fabricated FAPbBr₃ nanocrystals: the enhancing role of the ligand-assisted reprecipitation process. ACS Nano 12, 8808–8816 (2018). doi: 10.1021/acsnano.8b05172
[136]	Yu, X. C. et al. Tailoring the surface morphology and phase distribution for efficient perovskite electroluminescence. J. Phys. Chem. Lett. 11, 5877–5882 (2020). doi: 10.1021/acs.jpclett.0c01252
[137]	Liu, Y. et al. Efficient blue light-emitting diodes based on quantum-confined bromide perovskite nanostructures. Nat. Photonics 13, 760–764 (2019). doi: 10.1038/s41566-019-0505-4
[138]	Yantara, N. et al. Regulating vertical domain distribution in Ruddlesden-Popper perovskites for electroluminescence devices. J. Phys. Chem. Lett. 10, 7949–7955 (2019). doi: 10.1021/acs.jpclett.9b03057
[139]	Tsai, H. et al. Stable light-emitting diodes using phase-pure Ruddlesden-Popper layered perovskites. Adv. Mater. 30, 1704217 (2018). doi: 10.1002/adma.201704217
[140]	Lee, H. D. et al. Efficient Ruddlesden-Popper perovskite light-emitting diodes with randomly oriented nanocrystals. Adv. Funct. Mater. 29, 1901225 (2019). doi: 10.1002/adfm.201901225
[141]	Zhang, L. Q. et al. Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes. Nat. Commun. 8, 15640 (2017). doi: 10.1038/ncomms15640
[142]	Bi, C. et al. Non-wetting surface-driven high-aspect-ratio crystalline grain growth for efficient hybrid perovskite solar cells. Nat. Commun. 6, 7747 (2015). doi: 10.1038/ncomms8747
[143]	Zhao, B. D. et al. Efficient light-emitting diodes from mixed-dimensional perovskites on a fluoride interface. Nat. Electron. 3, 704–710 (2020). doi: 10.1038/s41928-020-00487-4
[144]	Wang, K. H. et al. Efficient and color-tunable quasi-2D CsPbBr_xCl_3-x perovskite blue light-emitting diodes. ACS Photonics 6, 667–676 (2019). doi: 10.1021/acsphotonics.8b01490
[145]	Meng, Y. et al. High performance and stable all-inorganic perovskite light emitting diodes by reducing luminescence quenching at PEDOT: PSS/perovskites interface. Org. Electron. 64, 47–53 (2019). doi: 10.1016/j.orgel.2018.10.014
[146]	Zhou, Y. M. et al. Improved efficiency of perovskite light-emitting diodes using a three-step spin-coated CH₃NH₃PbBr₃ emitter and a PEDOT: PSS/MoO₃-ammonia composite hole transport layer. Micromachines 10, 459 (2019). doi: 10.3390/mi10070459
[147]	Hong, K. & Lee, J. L. Review paper: recent developments in light extraction technologies of organic light emitting diodes. Electron. Mater. Lett. 7, 77–91 (2011). doi: 10.1007/s13391-011-0601-1
[148]	Salehi, A. et al. Recent advances in OLED optical design. Adv. Funct. Mater. 29, 1808803 (2019). doi: 10.1002/adfm.201808803
[149]	Kim, Y. H. et al. Molecular-scale strategies to achieve high efficiency and low efficiency roll-off in simplified solution-processed organic light-emitting diodes. Adv. Funct. Mater. 30, 2005292 (2020). doi: 10.1002/adfm.202005292
[150]	Chen, C. W. et al. Optical properties of organometal halide perovskite thin films and general device structure design rules for perovskite single and tandem solar cells. J. Mater. Chem. A 3, 9152–9159 (2015). doi: 10.1039/C4TA05237D
[151]	Lin, T. A. et al. Sky-blue organic light emitting diode with 37% external quantum efficiency using thermally activated delayed fluorescence from spiroacridine-triazine hybrid. Adv. Mater. 28, 6976–6983 (2016). doi: 10.1002/adma.201601675
[152]	Shi, X. B. et al. Optical energy losses in organic-inorganic hybrid perovskite light-emitting diodes. Adv. Optic. Mater. 6, 1800667 (2018). doi: 10.1002/adom.201800667
[153]	Chen, Z. M. et al. Utilization of trapped optical modes for white perovskite light-emitting diodes with efficiency over 12%. Joule https://doi.org/10.1016/j.joule.2020.12.008">https://doi.org/10.1016/j.joule.2020.12.008 (2021).
[154]	Motti, S. G. et al. Heterogeneous photon recycling and charge diffusion enhance charge transport in quasi-2D lead-halide perovskite films. Nano Lett. 19, 3953–3960 (2019). doi: 10.1021/acs.nanolett.9b01242
[155]	Stranks, S. D. et al. The physics of light emission in halide perovskite devices. Adv. Mater. 31, 1803336 (2019). doi: 10.1002/adma.201803336
[156]	Bi, W. T. et al. Efficient quasi-two-dimensional perovskite light-emitting diodes with improved multiple quantum well structure. ACS Appl. Mater. Interfaces 12, 1721–1727 (2020). doi: 10.1021/acsami.9b10186
[157]	Zou, Y. T. et al. Boosting perovskite light-emitting diode performance via tailoring interfacial contact. ACS Appl. Mater. Interfaces 10, 24320–24326 (2018). doi: 10.1021/acsami.8b07438
[158]	Cho, C. et al. The role of photon recycling in perovskite light-emitting diodes. Nat. Commun. 11, 611 (2020). doi: 10.1038/s41467-020-14401-1
[159]	Lu, J. X. et al. Ultrathin PEDOT: PSS enables colorful and efficient perovskite light-emitting diodes. Adv. Sci. 7, 2000689 (2020). doi: 10.1002/advs.202000689
[160]	Ziebarth, J. M. et al. Extracting light from polymer light-emitting diodes using stamped bragg gratings. Adv. Funct. Mater. 14, 451–456 (2004). doi: 10.1002/adfm.200305070
[161]	Cheng, Y. H. et al. Enhanced light outcoupling in a thin film by texturing meshed surfaces. Appl. Phys. Lett. 90, 091102 (2007). doi: 10.1063/1.2709920
[162]	Koo, W. H. et al. Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles. Nat. Photonics 4, 222–226 (2010). doi: 10.1038/nphoton.2010.7
[163]	Zou, W. et al. Minimising efficiency roll-off in high-brightness perovskite light-emitting diodes. Nat. Commun. 9, 608 (2018). doi: 10.1038/s41467-018-03049-7
[164]	Jiang, Y. Z. et al. Reducing the impact of Auger recombination in quasi-2D perovskite light-emitting diodes. Nat. Commun. 12, 336 (2021). doi: 10.1038/s41467-020-20555-9
[165]	Warby, J. H. et al. Revealing factors influencing the operational stability of perovskite light-emitting diodes. ACS Nano 14, 8855–8865 (2020). doi: 10.1021/acsnano.0c03516
[166]	Shang, Y. Q. et al. Quasi-2D inorganic CsPbBr₃ perovskite for efficient and stable light-emitting diodes. Adv. Funct. Mater. 28, 1801193 (2018). doi: 10.1002/adfm.201801193
[167]	Shang, Y. Q. et al. Highly stable hybrid perovskite light-emitting diodes based on Dion-Jacobson structure. Sci. Adv. 5, eaaw8072 (2019). doi: 10.1126/sciadv.aaw8072
[168]	Zhao, L. F. et al. Improved outcoupling efficiency and stability of perovskite light-emitting diodes using thin emitting layers. Adv. Mater. 31, 1805836 (2019). doi: 10.1002/adma.201805836
[169]	Babayigit, A. et al. Toxicity of organometal halide perovskite solar cells. Nat. Mater. 15, 247–251 (2016). doi: 10.1038/nmat4572
[170]	Lu, S. H. et al. Accelerated discovery of stable lead-free hybrid organic-inorganic perovskites via machine learning. Nat. Commun. 9, 3405 (2018). doi: 10.1038/s41467-018-05761-w
[171]	Qiu, J. J. et al. Stable, efficient near-infrared light-emitting diodes enabled by α/δ phase modulation. J. Phys. Chem. Lett. 10, 2101–2107 (2019). doi: 10.1021/acs.jpclett.9b00587
[172]	Kendall, K. R. et al. Recent developments in oxide ion conductors: aurivillius phases. Chem. Mater. 8, 642–649 (1996). doi: 10.1021/cm9503083
[173]	Chen, J. W. et al. Efficient and bright white light-emitting diodes based on single-layer heterophase halide perovskites. Nat. Photonics https://doi.org/10.1038/s41566-020-00743-1">https://doi.org/10.1038/s41566-020-00743-1 (2020).
[174]	Shen, P. F., Vogt, T. & Lee, Y. Pressure-induced enhancement of broad-band white light emission in butylammonium lead bromide. J. Phys. Chem. Lett. 11, 4131–4137 (2020). doi: 10.1021/acs.jpclett.0c01160
[175]	Jamaludin, N. F. et al. White electroluminescence from perovskite-organic heterojunction. ACS Energy Lett. 5, 2690–2697 (2020). doi: 10.1021/acsenergylett.0c01176
[176]	Ye, F. et al. Low-temperature soft-cover deposition of uniform large-scale perovskite films for high-performance solar cells. Adv. Mater. 29, 1701440 (2017). doi: 10.1002/adma.201701440
[177]	Chu, S. L. et al. Large-area and efficient perovskite light-emitting diodes via low-temperature blade-coating. Nat. Commun. 12, 147 (2021). doi: 10.1038/s41467-020-20433-4
[178]	Zhao, X. F. & Tan, Z. K. Large-area near-infrared perovskite light-emitting diodes. Nat. Photonics 14, 215–218 (2020). doi: 10.1038/s41566-019-0559-3
[179]	Wang, H. R. et al. A multi-functional molecular modifier enabling efficient large-area perovskite light-emitting diodes. Joule 4, 1977–1987 (2020). doi: 10.1016/j.joule.2020.07.002
[180]	Kim, D. B. et al. Uniform and large-area cesium-based quasi-2D perovskite light-emitting diodes using hot-casting method. Adv. Mater. Interfaces 7, 1902158 (2020). doi: 10.1002/admi.201902158
[181]	Spechler, J. A. et al. A transparent, smooth, thermally robust, conductive polyimide for flexible electronics. Adv. Funct. Mater. 25, 7428–7434 (2015). doi: 10.1002/adfm.201503342
[182]	Li, F. et al. Flexible QLED and OPV based on transparent polyimide substrate with rigid alicyclic asymmetric isomer. Org. Electron. 51, 54–61 (2017). doi: 10.1016/j.orgel.2017.09.010
[183]	Yao, H. Y. et al. From a flexible hyperbranched polyimide to a microporous polyimide network: Microporous architecture and carbon dioxide adsorption. Polymer 115, 176–183 (2017). doi: 10.1016/j.polymer.2017.03.035
[184]	Bade, S. G. R. et al. Fully printed halide perovskite light-emitting diodes with silver nanowire electrodes. ACS Nano 10, 1795–1801 (2016). doi: 10.1021/acsnano.5b07506
[185]	Zhao, L. F. et al. Influence of Bulky organo-ammonium halide additive choice on the flexibility and efficiency of perovskite light-emitting devices. Adv. Funct. Mater. 28, 1802060 (2018). doi: 10.1002/adfm.201802060
[186]	Liu, Y. et al. Fluorescent microarrays of in situ crystallized perovskite nanocomposites fabricated for patterned applications by using inkjet printing. ACS Nano 13, 2042–2049 (2019).
[187]	Jia, S. Q. et al. Highly luminescent and stable green quasi-2D perovskite-embedded polymer sheets by inkjet printing. Adv. Funct. Mater. 30, 1910817 (2020). doi: 10.1002/adfm.201910817
[188]	Zhang, H. H. et al. A two-dimensional Ruddlesden-Popper perovskite nanowire laser array based on ultrafast light-harvesting quantum wells. Angew. Chem. Int. Ed. 57, 7748–7752 (2018). doi: 10.1002/anie.201802515
[189]	Li, M. J. et al. Enhanced exciton and photon confinement in Ruddlesden-Popper perovskite microplatelets for highly stable low-threshold polarized lasing. Adv. Mater. 30, 1707235 (2018). doi: 10.1002/adma.201707235
[190]	Liang, Y. et al. Lasing from mechanically exfoliated 2D homologous Ruddlesden-Popper perovskite engineered by inorganic layer thickness. Adv. Mater. 31, 1903030 (2019). doi: 10.1002/adma.201903030
[191]	Cui, M. H. et al. Direct observation of competition between amplified spontaneous emission and auger recombination in quasi-two-dimensional perovskites. J. Phys. Chem. Lett. 11, 5734–5740 (2020). doi: 10.1021/acs.jpclett.0c01852
[192]	Li, M. L. et al. Amplified spontaneous emission based on 2D Ruddlesden-Popper perovskites. Adv. Funct. Mater. 28, 1707006 (2018). doi: 10.1002/adfm.201707006
[193]	Qin, C. J. et al. Stable room-temperature continuous-wave lasing in quasi-2D perovskite films. Nature 585, 53–57 (2020). doi: 10.1038/s41586-020-2621-1
[194]	Liang, D. et al. Color-pure violet-light-emitting diodes based on layered lead halide perovskite nanoplates. ACS Nano 10, 6897–6904 (2016). doi: 10.1021/acsnano.6b02683
[195]	Chen, Z. M. et al. High-performance color-tunable perovskite light emitting devices through structural modulation from bulk to layered film. Adv. Mater. 29, 1603157 (2017). doi: 10.1002/adma.201603157
[196]	Ren, Z. W. et al. Hole transport bilayer structure for quasi-2D perovskite based blue light-emitting diodes with high brightness and good spectral stability. Adv. Funct. Mater. 29, 1905339 (2019). doi: 10.1002/adfm.201905339
[197]	Pang, P. Y. et al. Rearranging low-dimensional phase distribution of quasi-2D perovskites for efficient sky-blue perovskite light-emitting diodes. ACS Nano 14, 11420–11430 (2020). doi: 10.1021/acsnano.0c03765
[198]	Shen, Y. et al. Interfacial potassium-guided grain growth for efficient deep-blue perovskite light-emitting diodes. Adv. Funct. Mater. https://doi.org/10.1002/adfm.202006736">https://doi.org/10.1002/adfm.202006736 (2020).
[199]	Zhang, Q. P. et al. Efficient metal halide perovskite light-emitting diodes with significantly improved light extraction on nanophotonic substrates. Nat. Commun. 10, 727 (2019). doi: 10.1038/s41467-019-08561-y
[200]	Shen, Y. et al. High-efficiency perovskite light-emitting diodes with synergetic outcoupling enhancement. Adv. Mater. 31, 1901517 (2019). doi: 10.1002/adma.201901517
[201]	Jeon, S. et al. Perovskite light-emitting diodes with improved outcoupling using a high-index contrast nanoarray. Small 15, 1900135 (2019). doi: 10.1002/smll.201900135
[202]	Zhang, Q. P. et al. Three-dimensional perovskite nanophotonic wire array-based light-emitting diodes with significantly improved efficiency and stability. ACS Nano 14, 1577–1585 (2020). doi: 10.1021/acsnano.9b06663
[203]	Liu, X. K. et al. Metal halide perovskites for light-emitting diodes. Nat. Mater. https://doi.org/10.1038/s41563-020-0784-7">https://doi.org/10.1038/s41563-020-0784-7 (2021).