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• A complex gradient passivation strategy was first proposed for inverted PSCs. • In(SCN 2 H 4) 3 Cl 3 effectively passivates defect states in bulk perovskite layer. • In(SCN 2 H 4) 3 Cl 3 facilitates hole extraction by modulating interface energy level alignment. • The efficiency and stability of inverted PSCs are significantly improved. To address the interfacial and bulk defects and mismatched energy band alignment at perovskite/hole transport layr (HTL) interface in inverted perovskite solar cells (PSCs), here a novel In(SCN 2 H 4) 3 Cl 3 complex diffusion doping strategy was proposed to construct CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 composite layer for poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA)-based inverted PSCs. The In(tu) 3 Cl 3 effectively promotes the quality of perovskite films with larger perovskite crystal grains and flatter and denser surfaces. Both theoretical and experimental results reveal that the In(SCN 2 H 4) 3 Cl 3 can not only passivate interfacial and bulk defects in perovskite layer, but also form a spatial separation of photogenerated charges through CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 heterojunction interface, which effectively decreases the charge recombination and enhances charge separation and transport property in PSCs. Moreover, the In(SCN 2 H 4) 3 Cl 3 optimizes energy band alignment at perovskite/PTAA interface and creates a polarization electric field at the PTAA/In(SCN 2 H 4) 3 Cl 3 interface directing toward PTAA layer, which promotes the hole transfer from the CH 3 NH 3 PbI 3 to the PTAA and increases the open-circuit voltage (V oc). As a consequence, optimized inverted PSCs with CH 3 NH 3 PbI 3 :In(SCN 2 H 4) 3 Cl 3 layer achieve high efficiency of 21.25 % and also show a significantly improved long-term stability under different aging test conditions. Our work provides a valuable guide for designing efficient and stable inverted PSCs. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) has an important influence on the power conversion efficiency (PCE) and stability of n‐i‐p planar perovskite solar cells (PSCs). This paper presents an N‐type semiconductor material, (CH3)2Sn(COOH)2 (abbreviated as CSCO) that is synthesized and prepared for the first time as an ETL for n‐i‐p planar PSCs, which leads to a high PCE of 22.21% after KCl treatment, one of the highest PCEs of n‐i‐p planar PSCs to date. Further analysis reveals that the high PCE is attributed to the excellent conductivity of CSCO because of its more delocalized electron cloud distribution due to its unique −O=C−O− group, and to the defect passivation of the Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 (denoted as CsFAMA) perovskite through the interaction between the O (Sn) atoms of CSCO and the Pb (halogen) atoms of CsFAMA at CSCO/CsFAMA interface, while the traditional ETL materials such as SnO2 film lack this function. In addition to the high PCE, the optimal PSCs using CSCO as ETL show remarkable stability, retaining over 83% of its initial PCE without encapsulation after 130 days of storage in ambient conditions (≈25 °C at ≈40% humidity), much better than the traditional SnO2‐based n‐i‐p PSCs. [ABSTRACT FROM AUTHOR]

To improve the power conversion efficiency (PCE) and stability of inverted perovskite solar cells (PSCs) prepared in humid air (RH = 55%), a new zinc oxide (ZnO):TIPD composite film is inserted between PCBM layer and Ag electrode for the first time. Compared to the single PCBM layer, the formed PCBM/ZnO:TIPD electron transport layer (ETL) has better coverage on the perovskite layer and more effective charge extraction ability from the perovskite layer. The insertion of ZnO:TIPD film effectively suppress the charge recombination at perovskite/ETL interface. Besides, the PCBM/ZnO:TIPD layer has better ability to prevent moisture from penetrating into the perovskite layer than single PCBM film. For these reasons, the PCE and stability of the PSCs with the PCBM/ZnO:TIPD are significantly improved compared to the PSCs with single PCBM (or ZnO:TIPD) layer. The highest efficiency of the cell with PCBM/ZnO:TIPD ETL reaches (13.7 ± 0.4)% in ambient atmosphere, which is 1.20 times that of the PSCs with PCBM only. • The ZnO:TIPD composite film are fabricated for the first time. • The effect of the ZnO:TIPD film on charge separation and extraction is studied. • The efficiency and stability of the perovskite solar cells are significantly improved. [ABSTRACT FROM AUTHOR]