[1] [1] A Kojima, TeshimaK， ShiraiY， et al KojimaA，, K Teshima, TeshimaK， ShiraiY， et al KojimaA，, Y Shirai and TeshimaK， ShiraiY， et al KojimaA，. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. Journal of the American Chemical Society. 131(17), 6050-6051(2009).

[2] [2] H S Kim, S， LeeC R， ImJ H， et al KimH, C R Lee, S， LeeC R， ImJ H， et al KimH, J H Im and S， LeeC R， ImJ H， et al KimH. Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9%. Sci Rep. 2(1), (2012).

[3] [3] . Research cell record efficiency chart. (0).

[4] [4] L Meng, YouJ， GuoT F， et al MengL，, J You, YouJ， GuoT F， et al MengL，, T F Guo and YouJ， GuoT F， et al MengL，. Recent advances in the inverted planar structure of perovskite solar cells. Accounts of Chemical Research. 49(1), 155-165(2016).

[5] [5] H Tsai, NieW， BlanconJ， et al TsaiH，, W Nie, NieW， BlanconJ， et al TsaiH，, J Blancon and NieW， BlanconJ， et al TsaiH，. High-efficiency two-dimensional ruddlesden???popper perovskite solar cells. Nature. 536(7616), 312-316(2016).

[6] [6] N Li, ZhuZ， ChuehC， et al LiN，, Z Zhu, ZhuZ， ChuehC， et al LiN，, C Chueh and ZhuZ， ChuehC， et al LiN，. Mixed cation FAxPEA1–xPbI3 with enhanced phase and ambient stability toward high‐performance perovskite solar cells. Advanced Energy Materials. 7(1), (2017).

[7] [7] F Zhang, LuH， TongJ， et al ZhangF，, H Lu, LuH， TongJ， et al ZhangF，, J Tong and LuH， TongJ， et al ZhangF，. Advances in two-dimensional organic–inorganic hybrid perovskites. Energy and Environmental Science. 13(4), 1154-1186(2020).

[8] [8] J Zhang, QinJ J， WangM， et al ZhangJ，, J J Qin, QinJ J， WangM， et al ZhangJ，, M Wang and QinJ J， WangM， et al ZhangJ，. Uniform permutation of quasi-2D perovskites by vacuum poling for efficient， high-fill-factor solar cells. Joule. 3(12), 3061-3071(2019).

[9] [9] T Luo, ZhangY， XuZ， et al LuoT，, Y Zhang, ZhangY， XuZ， et al LuoT，, Z Xu and ZhangY， XuZ， et al LuoT，. Compositional control in 2D perovskites with alternating cations in the interlayer space for photovoltaics with efficiency over 18%. Advanced Materials. 31(44), (2019).

[10] [10] H Min, KimM， LeeS， et al MinH，, M Kim, KimM， LeeS， et al MinH，, S Lee and KimM， LeeS， et al MinH，. Efficient， stable solar cells by using inherent bandgap of α-phase formamidinium lead iodide. Science. 366(6466), 749-753(2019).

[11] [11] X Lian, ChenJ， ZhangY， et al LianX，, J Chen, ChenJ， ZhangY， et al LianX，, Y Zhang and ChenJ， ZhangY， et al LianX，. Solvation effect in precursor solution enables over 16% efficiency in thick 2D perovskite solar cells. Journal of Materials Chemistry A. 7(33), 19423-19429(2019).

[12] [12] S Wu, LiZ， ZhangJ， et al WuS，, Z Li, LiZ， ZhangJ， et al WuS，, J Zhang and LiZ， ZhangJ， et al WuS，. Efficient large guanidinium mixed perovskite solar cells with enhanced photovoltage and low energy losses. Chemical Communications. 55(30), 4315-4318(2019).

[13] [13] B Saparov, MitziD B SaparovB， and D B Mitzi. Organic–inorganic perovskites： structural versatility for functional materials design. Chemical Reviews. 116(7), 4558-4596(2016).

[14] [14] H Lin, ZhouC， TianY， et al LinH，, C Zhou, ZhouC， TianY， et al LinH，, Y Tian and ZhouC， TianY， et al LinH，. Low-dimensional organometal halide perovskites. ACS Energy Letters. 3(1), 54-62(2018).

[15] [15] V M GoldschmidtV M Goldschmidt. Die Gesetze der Krystallochemie. Naturwissenschaften. 14(21), 477-485(1926).

[16] [16] C C Stoumpos, C， CaoD H， ClarkD J， et al StoumposC, D H Cao, C， CaoD H， ClarkD J， et al StoumposC, D J Clark and C， CaoD H， ClarkD J， et al StoumposC. Ruddlesden–popper hybrid lead iodide perovskite 2D homologous semiconductors. Chemistry of Materials. 28(8), 2852-2867(2016).

[17] [17] J Hu, YanL， YouW HuJ，, L Yan, YanL， YouW HuJ， and W You. Two‐dimensional organic–inorganic hybrid perovskites： a new platform for optoelectronic applications. Advanced Materials. 30(48), (2018).

[18] [18] S Ma, CaiM， ChengT， et al MaS，, M Cai, CaiM， ChengT， et al MaS，, T Cheng and CaiM， ChengT， et al MaS，. Two-dimensional organic-inorganic hybrid perovskite： from material properties to device applications. Science China Materials. 61(10), 1257-1277(2018).

[19] [19] M Kumagai, TakagaharaT KumagaiM， and T Takagahara. Excitonic and nonlinear-optical properties of dielectric quantum-well structures. Physical Review B Condensed Matter. 40(18), 12359-12381(1990).

[20] [20] L V KeldyshL V Keldysh. Coulomb interaction in thin semiconductor and semimetal films. Soviet Journal of Experimental & Theoretical Physics Letters. 29(1), 658-661(1979).

[21] [21] X Hong, IshiharaT， NurmikkoA V HongX，, T Ishihara, IshiharaT， NurmikkoA V HongX， and A V Nurmikko. Dielectric confinement effect on excitons in Pbl4-based layered semiconductors. Physrevb. 45(12), (1992).

[22] [22] T Ishihara, HongX， DingJ， et al IshiharaT，, X Hong, HongX， DingJ， et al IshiharaT，, J Ding and HongX， DingJ， et al IshiharaT，. Dielectric confinement effect for exciton and biexciton states in PbI4-based two-dimensional semiconductor structures. Surface Science. 267(1-3), 323-326(1992).

[23] [23] D H Cao, H， StoumposC C， FarhaO K， et al CaoD, C C Stoumpos, H， StoumposC C， FarhaO K， et al CaoD, O K Farha and H， StoumposC C， FarhaO K， et al CaoD. 2D homologous perovskites as light-absorbing materials for solar cell applications. Journal of the American Chemical Society. 137(24), 7843-7850(2015).

[24] [24] X Yang, ZhangX， DengJ， et al YangX，, X Zhang, ZhangX， DengJ， et al YangX，, J Deng and ZhangX， DengJ， et al YangX，. Efficient green light-emitting diodes based on quasi-two-dimensional composition and phase engineered perovskite with surface passivation. Nature Communications. 9(1), (2018).

[25] [25] L N Quan, N， YuanM， CominR， et al QuanL, M Yuan, N， YuanM， CominR， et al QuanL, R Comin and N， YuanM， CominR， et al QuanL. Ligand-stabilized reduced-dimensionality perovskites. Journal of the American Chemical Society. 138(8), 2649-2655(2016).

[26] [26] I C Smith, C， HokeE T， SolisibarraD， et al SmithI, E T Hoke, C， HokeE T， SolisibarraD， et al SmithI, D Solisibarra and C， HokeE T， SolisibarraD， et al SmithI. A layered hybrid perovskite solar‐cell absorber with enhanced moisture stability. Angewandte Chemie. 53(42), 11232-11235(2014).

[27] [27] A Miyata, MitiogluA A， PlochockaP， et al MiyataA，, A A Mitioglu, MitiogluA A， PlochockaP， et al MiyataA，, P Plochocka and MitiogluA A， PlochockaP， et al MiyataA，. Direct measurement of the exciton binding energy and effective masses for charge carriers in organic-inorganic tri-halide perovskites. Nature Physics. 11(7), 582-587(2015).

[28] [28] T M Koh, M， ThirumalK， SooH S， et al KohT, K Thirumal, M， ThirumalK， SooH S， et al KohT, H S Soo and M， ThirumalK， SooH S， et al KohT. Multidimensional perovskites： a mixed cation approach towards ambient stable and tunable perovskite photovoltaics. Chemsuschem. 9(18), 2541-2558(2016).

[29] [29] R L Milot, L， SuttonR J， EperonG E， et al MilotR, R J Sutton, L， SuttonR J， EperonG E， et al MilotR, G E Eperon and L， SuttonR J， EperonG E， et al MilotR. Charge-carrier dynamics in 2D hybrid metal-halide perovskites. Nano Letters. 16(11), 7001-7007(2016).

[30] [30] E R Dohner, R， JaffeA， BradshawL R， et al DohnerE, A Jaffe, R， JaffeA， BradshawL R， et al DohnerE, L R Bradshaw and R， JaffeA， BradshawL R， et al DohnerE. Intrinsic white-light emission from layered hybrid perovskites. Journal of the American Chemical Society. 136(38), 13154-13157(2014).

[31] [31] H Mathieu, LefebvreP， ChristolP MathieuH，, P Lefebvre, LefebvreP， ChristolP MathieuH， and P Christol. Simple analytical method for calculating exciton binding energies in semiconductor quantum wells. Physical Review B. 46(7), 4092-4101(1992).

[32] [32] X HeX He. Excitons in anisotropic solids： the model of fractional-dimensional space. Physical Review B. 43(3), 2063-2069(1991).

[33] [33] L C Andreani, C， PasquarelloA AndreaniL and A Pasquarello. Theory of excitons in GaAs-Ga1-xAlxAs quantum wells including valence band mixing. Superlattices & Microstructures. 5(1), 59-63(1989).

[34] [34] S M SzeS M Sze. Physics of semiconductor devices. Amsterdam ： Wiley. (1981).

[35] [35] J Even, PedesseauL， JancuJ， et al EvenJ，, L Pedesseau, PedesseauL， JancuJ， et al EvenJ，, J Jancu and PedesseauL， JancuJ， et al EvenJ，. Importance of spin-orbit coupling in hybrid organic/inorganic perovskites for photovoltaic applications. Journal of Physical Chemistry Letters. 4(7), 2999-3005(2013).

[36] [36] L Pedesseau, SaporiD， TraoreB， et al PedesseauL，, D Sapori, SaporiD， TraoreB， et al PedesseauL，, B Traore and SaporiD， TraoreB， et al PedesseauL，. Advances and promises of layered halide hybrid perovskite semiconductors. ACS Nano. 10(11), 9776-9786(2016).

[37] [37] Z G YuZ G Yu. Effective-mass model and magneto-optical properties in hybrid perovskites. Scientific Reports. 6(1), (2016).

[39] [39] T Ishihara, TakahashiJ， GotoT IshiharaT，, J Takahashi, TakahashiJ， GotoT IshiharaT， and T Goto. Optical properties due to electronic transitions in two-dimensional semiconductors （CnH2n+1NH3）2PbI4. Physical Review B. 42(17), 11099-11107(1990).

[41] [41] D B Straus, B， ParraS H， IotovN， et al StrausD, S H Parra, B， ParraS H， IotovN， et al StrausD, N Iotov and B， ParraS H， IotovN， et al StrausD. Direct observation of electron–phonon coupling and slow vibrational relaxation in organic–inorganic hybrid perovskites. Journal of the American Chemical Society. 138(42), 13798-13801(2016).

[42] [42] D Cortecchia, YinJ， BrunoA， et al CortecchiaD，, J Yin, YinJ， BrunoA， et al CortecchiaD，, A Bruno and YinJ， BrunoA， et al CortecchiaD，. Polaron self-localization in white-light emitting hybrid perovskites. Journal of Materials Chemistry C. 5(11), 2771-2780(2017).

[43] [43] H Zhu, MiyataK， FuY， et al ZhuH，, K Miyata, MiyataK， FuY， et al ZhuH，, Y Fu and MiyataK， FuY， et al ZhuH，. Screening in crystalline liquids protects energetic carriers in hybrid perovskites. Science. 353(6306), 1409-1413(2016).

[44] [44] X Wu, TrinhM T， NiesnerD， et al WuX，, M T Trinh, TrinhM T， NiesnerD， et al WuX，, D Niesner and TrinhM T， NiesnerD， et al WuX，. Trap states in lead iodide perovskites. Journal of the American Chemical Society. 137(5), 2089-2096(2015).

[45] [45] D B Straus, B， KaganC R StrausD and C R Kagan. Electrons， excitons， and phonons in two-dimensional hybrid perovskites： connecting structural， optical， and electronic properties. The Journal of Physical Chemistry Letters. 9(6), 1434-1447(2018).

[46] [46] F L Pratt, L， WongK S， HayesW， et al PrattF, K S Wong, L， WongK S， HayesW， et al PrattF, W Hayes and L， WongK S， HayesW， et al PrattF. Springer series in solid-state sciences. Journal of Physics C Solid State Physics. 20(3), (2000).

[47] [47] E R Dohner, R， HokeE T， KarunadasaH I DohnerE, E T Hoke, R， HokeE T， KarunadasaH I DohnerE and H I Karunadasa. Self-assembly of broadband white-light emitters. Journal of the American Chemical Society. 136(5), 1718-1721(2014).

[48] [48] J Liu, LengJ， WuK， et al LiuJ，, J Leng, LengJ， WuK， et al LiuJ，, K Wu and LengJ， WuK， et al LiuJ，. Observation of internal photoinduced electron and hole separation in hybrid two-dimentional perovskite films. Journal of the American Chemical Society. 139(4), (2017).

[49] [49] Y Zhang, WangR， LiY， et al ZhangY，, R Wang, WangR， LiY， et al ZhangY，, Y Li and WangR， LiY， et al ZhangY，. Optical properties of two-dimensional perovskite films of （C6H5C2H4NH3）2［PbI4］ and （C6H5C2H4NH3）2 （CH3NH3）2［Pb3I10］. Journal of Physical Chemistry Letters. 10(1), 13-19(2019).

[50] [50] K Thirumal, ChongW K， XieW， et al ThirumalK，, W K Chong, ChongW K， XieW， et al ThirumalK，, W Xie and ChongW K， XieW， et al ThirumalK，. Morphology-independent stable white-light emission from self-assembled two-dimensional perovskites driven by strong exciton-phonon coupling to the organic framework. Chemistry of Materials. 29(9), 3947-3953(2017).

[51] [51] D Ramirez, Ignacio UribeJ， FrancavigliaL， et al RamirezD，, J Ignacio Uribe, Ignacio UribeJ， FrancavigliaL， et al RamirezD，, L Francaviglia and Ignacio UribeJ， FrancavigliaL， et al RamirezD，. Photophysics behind highly luminescent two-dimensional hybrid perovskite （CH3（CH2）2NH3）2（CH3NH3）2Pb3Br10 thin films. Journal of Materials Chemistry C. 6(23), 6216-6221(2018).

[52] [52] K Wu, BeraA， MaC， et al WuK，, A Bera, BeraA， MaC， et al WuK，, C Ma and BeraA， MaC， et al WuK，. Temperature-dependent excitonic photoluminescence of hybrid organometal halide perovskite films. Physical Chemistry Chemical Physics. 16(41), 22476-22481(2014).