Iodine vacancies (V I ) and undercoordinated Pb 2+ on the surface of all-inorganic perovskite films are mainly responsible for nonradiative charge recombination. An environmentally benign material, histamine (HA), is used to passivate the V I in perovskite films. A theoretical study shows that HA bonds to the V I on the surface of the perovskite film via a Lewis base-acid interaction; an additional hydrogen bond (H-bond) strengthens such interaction owing to the favorable molecular configuration of HA. Undercoordinated Pb 2+ and Pb clusters are passivated, leading to significantly reduced surface trap density and prolonged charge lifetime within the perovskite films. HA passivation also induces an upward shift of the energy band edge of the perovskite layer, facilitating interfacial hole transfer. The combination of the above raises the solar cell efficiency from 19.5 to 20.8 % under 100 mW cm À2 illumination, the highest efficiency so far for inorganic metal halide perovskite solar cells (PSCs).

We developed a versatile and environmentally friendly solution approach for the fabrication of a variety of metal sulfide nanocrystal thin films. Metal oxides, metal hydroxides, metal chlorides, metal acetates, and metal acetylacetonates can be used as the starting materials and dissolved in thioglycolic acid and ethanolamine, forming many types of metal–organic precursor solutions. High quality CdS, SnS, CuInS2, CuSbS2, Cu2ZnSnS4, Cu­(In0.7Ga0.3)­S2, and luminescent Ag-doped Zn x Cd1–x S nanocrystal thin films have been successfully prepared by spin-coating their corresponding metal precursor solutions. Cu2ZnSn­(S,Se)4 thin film solar cell with a power conversion efficiency of 6.83% has been realized by this versatile method.

PbI 2 -EMIMHSO 4 intermediates, finally enlarged the grain size, decreased the trap density, and relaxed the lattice strain of perovskite. The synergetic effects enable us to fabricate ambient blade-coating high-performance CsPbI 3 solar cells with PCEs as high as 20.01% under 1 sun illumination (100 mW cm −2 ) and 37.24% under indoor light illumination (1000 lux, 365 µW cm −2 ); both are the highest for the printed all-inorganic cells for corresponding applications. More importantly, the PCEs of CsPbI 3 -EMIMHSO 4 -based PSCs without any encapsulation retained 95% of the initial PCE value after 1000 h aging under ambient condition. Considering the simplicity and availability of this approach, our study offers an effective materials strategy to passivate crystal defect and regulate interfacial energy alignment for upscaling high-performance and long-term stable PSCs under ambient conditions.Research data are not shared.

The efficiency of earth‐abundant Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is considerably lower than the Shockley–Queisser limit. One of the main reasons for this is the presence of deleterious cation disordering caused by SnZn antisite and 2CuZn+SnZn defect clusters, resulting in a short minority carrier lifetime and significant band tailing, leading to a large open‐circuit voltage deficit, and hence, low efficiency. In this study, Ga‐doping is used to increase the CZTSSe solar cell efficiency to as high as 12.3%, one of the highest for this type of cells. First‐principles calculations show that the preference of Ga3+ occupying Zn and Sn sites has a benign effect on suppressing the formation of the SnZn deep donor defects by upwardly shifting the Fermi level, which is further confirmed by deep‐level transient spectroscopy characterization. Besides, the Ga dopants can also form defect‐dopant clusters, such as GaZn+CuZn and GaZn+GaSn, which also have positive effects on suppressing the band‐tailing states. The defect engineering via Ga3+‐doping may suppress the band‐tailing defect with a decreased Urbach energy, elevate the minority carrier lifetime, and in the end, enhance the VOC from 473 to 515 mV. These results provide a new route to further increase CZTSSe‐based solar cell efficiency by defect engineering.