Organic-inorganic hybrid perovskite solar cells (PSCs) based on tin (Sn) have attracted widespread attention due to their excellent optical and electrical properties similar to lead (Pb)-based analog and more importantly, these Sn-based perovskites owning intrinsic low-toxicity features have broader commercial application prospect. [1][2][3] And compared to Pb-based analog, Sn-based perovskite features a smaller optical bandgap and a more rapid charge-carrier mobility, both of which enable it to absorb more incident solar light and convert the light into more free carriers and then efficiently transport these carriers toward electrodes of PSCs. [3][4][5][6][7][8][9] Unfortunately, Sn-based perovskites suffer from fast oxidation of Sn 2+ to Sn 4+ and poor stability issue. [3,[9][10][11][12][13][14] Low open-circuit voltage (V oc ) also limits further increase of this kind of PSCs in power conversion efficiency (PCE). [15][16][17][18] Dimensionality adjustment from 3D to 2D or 2D/3D mixing is an effective strategy to significantly enhance stability, V oc , or even film morphology. [19][20][21][22][23][24][25] Relative to their 3D analogs, 2D or quasi-2D perovskites possess superior long-term durability and moisture tolerance since they own layered structure consisting of one or several layers of octahedra sandwiched between hydrophobic organic ligands, e.g., butylammonium and phenylethylammonium (PEA), and these hydrophobic organic ligands can protect the perovskite material from moisture and oxygen penetration. [18,[24][25][26][27][28] However, the presence of these organic spacer cations leads to the anisotropy characteristics of the crystal. The inclusion of 2D and quasi-2D perovskite quantum wells affects carrier transport and seriously blocks the charge transport along the vertical direction, which greatly reduces the device performance. [28][29][30][31][32][33][34] Therefore, manipulation of the growth crystallization of low-dimensional tin-based perovskites toward perpendicular orientation to the substrate surface is vital and some coadditives, e.g., NH 4 Cl, [35] PEA cations, [26,36] or cosolvent like N,N-dimethylformamide (DMF) [37] have been added to form preferential orientation perpendicular to the substrate. 2D/3D mixed tin (Sn)-based perovskites serving as excellent active layers possess a potential for enhancing film/device stabilities, open-circuit voltage, and power conversion efficiency (PCE) of perovskite solar cells (PSCs).Unfortunately, the poor morphology and low film coverage of these 2D/3D perovskites jeopardize their device performance and stability. Herein, doping of hydroxyl-rich d-sorbitol into hole transport layer poly(3,4-ethenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) can effectively address the PEDOT:PSS/perovskite interfacial issues. The multihydroxyl groups from d-sorbitol can sufficiently anchor iodide ions ([SnI 6 ] 4− or free I − ) of PEA 0.1 (FA 0.75 MA 0.25 ) 0.9 SnI 3 perovskite via hydrogen bond, which not only introduces more nucleation sites with improved crystall...

The C6H8N2O2·2HCl additive is first doped into an FA0.75MA0.25SnI3 precursor and plays a positive role in suppressing the generation of Sn4+ and promoting the formation of large-size crystal grains in FA0.75MA0.25SnI3 perovskite films.

Stability and efficiency issues are closely related with poor perovskite film quality in perovskite solar cells (PSCs). Herein, 2‐aminophenol (C6H7NO) and 2‐amino‐4‐fluorophenol (C6H6FNO) are introduced to improve film quality of FA0.75MA0.25SnI3, both of which consist of —NH2 and —OH groups, and the latter also contains —F group. The experimental and theoretical analyses show both —NH2 and —OH groups interact with I of the SnI64− octahedron via hydrogen bond and fluorinated group with low surface energy causes spontaneous migration of C6H6FNO to solution–air surface and induces initial crystal nucleation and growth from surface, both of which contribute to improved film morphology and crystallinity and suppressed Sn2+ oxidation via reducing defect‐state density and nonradiative recombination. The F atom of C6H6FNO facing outward protects FA0.75MA0.25SnI3 from water penetration due to its hydrophobic feature. The C6H6FNO‐doped PSC acquires a champion efficiency of 9.50% and a long‐term stability of >800 h (80% efficiency remained in N2).