Fig. 1. (Color online) (a) The structure and transition of CsPbI₃ phases versus temperature. Reproduced with permission^[46]. Copyright 2018, American Chemical Society Publications. (b) The transition of CsPbI₃ thermal phase and their transition mechanism. Reproduced with permission^[35]. Copyright 2019, Science Publishing Group. (c) Schematic of bonding/antibonding orbitals in CsPbX₃. Reproduce with permission^[54]. Copyright 2016, American Chemical Society Publications. (d) Electronic band structure of CsPbI₃ calculated by DFT and (e) tight-binding model. Reproduced with permission^[46]. Copyright 2018, American Chemical Society Publications.

Fig. 2. (Color online) (a) The diagrammatic of HI fabricated CsPbI₃. Reproduced with permission^[42]. Copyright 2015, The Royal Society of Chemistry. (b) Schematic of using HPbI₃ to fabricate FAPbI₃ PSCs. Reproduced with permission^[65]. Copyright 2015, Wiley-VCH Publications. (c) Detail information of PbI₂ and HPbI₃ fabricated perovskite film. Reproduced with permission^[69]. Copyright 2018, Wiley-VCH Publications. (d) The molecular structure of FA and DMA, and the tolerance factor of corresponding perovskite (CsPbI₃, Cs_0.7DMA_0.3PbI₃ and DMAPbI₃). Reproduced with permission^[71]. Copyright 2018, Nature Publishing Group.

Fig. 3. (Color online) (a) Schematic illustration the fabrication process of Cs_xDMA_1–xPbI₃. Reproduced with permission^[72]. Copyright 2019, Elsevier Inc Publications. (b) Schematic diagram of using DMAI additive to form CsPbI₃ films. Reproduced with permission^[74]. Copyright 2019, Wiley-VCH Publications. (c) The changeable component of DMAI-fabricated perovskite versus annealing temperature. Reproduced with permission^[75]. Copyright 2020, American Chemical Society Publications. (d) Schematic diagram of DMAPbI₃ synthesis process and the information of corresponding perovskite. Reproduced with permission^[76]. Copyright 2019, Wiley-VCH Publications.

Fig. 4. (Color online) (a) The detail information of PbI₂^.HI and PbI₂ fabricated perovskite, inserted pictures are their digital photos. Reproduced with permission^[78]. Copyright 2017, Wiley-VCH Publications. (b) The diagram of PbI₂ and HPbI₃ fabricated CsPbI₃ film, respectively. Reproduced with permission^[68]. Copyright 2018, American Chemical Society Publications. (c) Schematic of PEA⁺ organic ligand treatment on CsPbI₃ thin film. Reproduced with permission^[79]. Copyright 2018, Elsevier Inc Publications. (d) Diagram illustrates the mechanism of with/without OTG passivation. Reproduced with permission^[80]. Copyright 2019, Wiley-VCH Publications.

Fig. 5. (Color online) (a) Schematic illustration of CHI crack-filling interface engineering. Reproduced with permission^[73]. Copyright 2019, Science Publishing Group. (b) Schematic diagram CsPbI₃ crystal formation by using HI and H₂O. Reproduced with permission^[83]. Copyright 2018, American Chemical Society Publications. (c) Mechanism of STCG-CsPbI₃ film formation by assistant of ADMA molecule. Reproduced with permission^[84]. Copyright 2020, Wiley-VCH Publications. (d) The schematic illustration of HI and PEAI do on the CsPbI₃. Reproduced with permission^[43]. Copyright 2018, Nature Publishing Group.

Fig. 6. (Color online) (a) The structure and decomposition energies of different n values PEA₂Cs_n-1Pb_nX_3n+1. Reproduced with permission^[97]. Copyright 2018, Elsevier Inc Publications. (b) The controllable n values and structures of PEA₂Cs_n-1Pb_nX_3n+1. Reproduced with permission^[98]. Copyright 2019, Wiley-VCH Publications. (c) Schematic illustration the fabrication process of shell ligand, HPbI₃, H₂PbI₄ and in-suit assembled of them. Reproduced with permission^[101]. Copyright 2019, Wiley-VCH Publications.

Table 1. Photovoltaic parameters of CsPbI₃ PSCs fabricated by HI hydrolysis-derived intermediate.