[1] Jeon N J, Na H, Jung E H, et al. A fluorene-terminated hole-transporting material for highly efficient and stable perovskite solar cells [J]. Nature Energy, 2018, 3(8): 682-689.
[2] Prochowicz D, Runjhun R, Tavakoli M M, et al. Engineering of perovskite materials based on formamidinium and cesium hybridization for high-efficiency solar cells [J]. Chemistry of Materials, 2019, 31(5): 1620-1627.
[3] Slayney A H, Smaha R W, Smith I C, et al. Chemical approaches to addressing the instability and toxicity of lead-halide perovskite absorbers [J]. Inorganic Chemistry, 2017, 5(1): 46-55.
[4] Stoumpos C C, Malliakas C D, Kanatzidis M G. Semiconducting tin and lead iodide perovskites with organic cations: Phase transitions, high mobilities, and near-infrared photoluminescent properties [J]. Inorganic Chemistry, 2013, 52(15): 9019-9038.
[5] Shockley W, Queisser H J. Detailed balance limit of efficiency of p-n junction solar cells [J]. Journal of Applied Physics, 1961, 32: 510-519.
[6] Babayigit A, Thanh D D, Ethirajan A, et al. Assessing the toxicity of Pb- and Sn-based perovskite solar cells in model organism danio rerio [J]. Scientific Reports, 2016, 6: 18721.
[7] Jokar E, Chien C H, Tsai C M, et al. Robust Tin-based perovskite solar cells with hybrid organic cations to attain efficiency approaching 10% [J]. Advanced Materials, 2019, 31(2): 1804835.
[8] Qiu X, Cao B, Yuan S, et al. From unstable CsSnI3 to air-stable Cs2SnI6: A lead-free perovskite solar cell light absorber with bandgap of 1.48 eV and high absorption coefficient [J]. Solar Energy Materials and Solar Cells, 2017, 159: 227-234.
[9] Prasanna R, Gold-Parker A, Leijtens T, et al. Band gap tuning via lattice contraction and octahedral tilting in perovskite materials for photovoltaics [J]. Journal of the American Chemical Society, 2017, 139(32): 11117-11124.
[10] Eperon G E, Leijtens T, Bush K A, et al. Perovskite-perovskite tandem photovoltaics with optimized band gaps [J]. Science, 2016, 354(6314): 861-865.
[11] Hao F, Stoumpos C C, Chang R P H. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells [J]. Journal of the American Chemical Society, 2014, 13(22): 8094-8099.
[12] Chen Q, Zhou H, Luo S, et al. Controllable self-induced passivation of hybrid lead iodide perovskites toward high performance solar cells [J]. Nano Letters, 2014, 14(7): 4158-4163.
[13] Abdelhady A L, Saidaminov M, Murali B, et al. Heterovalent dopant incorporation for bandgap and type engineering of perovskite crystals [J]. Journal of Physical Chemistry Letters, 2016, 7(2): 295-301.
[14] Kumar M H, Dharani S, Leong W L, et al. Lead-free halide perovskite solar cells with high photocurrents realized through vacancy modulation [J]. Advanced Materials, 2014, 2(41): 7122-7127.
[15] Xu J, Buin A, Ip A H, et al. Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes [J]. Nature Communications, 2015, (1): 7081-7088.
[16] Buin A, Pietsch P, Xu J, et al. Materials processing routes to trap-free halide perovskites [J]. Nano Letters, 2014, 14(11): 6281-6286.
[17] Shao Y, Xiao Z, Bi C, et al. Origin and elimination of photocurrent hysteresis by fullerene passivation in CH3NH3PbI3 planar heterojunction solar cells [J]. Nature Communications, 2014, 5(1): 5784-5790.
[18] Koh T M, Krishnamoorthy T, Yantara N, et al. Formamidinium tin-based perovskite with low Eg for photovoltaic applications [J]. Journal of Materials Chemistry A, 2015, 3: 14996-15000.
[19] Liao W, Zhao D, Yu Y, et al. Lead-free inverted planar formamidinium tin triiodide perovskite solar cells achieving power conversion efficiencies up to 6.22% [J]. Advanced Materials, 2016, 28(42): 9333-9340.
