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).

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.

All-inorganic perovskite CsPbI 3 has attracted extensive attention recently because of its excellent thermal and chemical stability. However, its photovoltaic performance is hindered by large energy losses (E loss ) due to the presence of point defects. In addition, hydroiodic acid (HI) is currently employed as a hydrolysis-derived precursor of intermediate compounds, which often leads to a small amount of organic residue, thus undermining its chemical stability. Herein, an in-situ hot oxygen cleansing with superior passivation (HOCP) for the triple halide-mixed CsPb(I 2.85 Br 0.149 Cl 0.001 ) perovskite solar cells (abbreviated as CsPbTh 3 ) deposited in an ambient atmosphere to reduce the E loss to as low as 0.48 eV for the power conversion efficiency (PCE) to reach 19.65% is demonstrated. It is found that the hot oxygen treatment effectively removes the organic residues. Meanwhile, it passivates halide vacancies, hence reduces the trap states and nonradiative recombination losses within the perovskite layer. As a result, the PCE is increased significantly from 17.15% to 19.65% under 1 sun illumination with an open-circuit voltage enlarged to 1.23 from 1.14 V, which corresponds to an E loss reduction from 0.57 to 0.48 eV. Also, the HOCP-treated devices exhibit better long-term stability. This insight should pave a way for decreasing nonradiative charge recombination losses for high-performance inorganic perovskite photoelectronics.

CsPbI3−xBrx‐based organic‐free perovskite has emerged as a superstar photovoltaic material not only because of its superior photoelectronic properties but also its outstanding thermal and chemical stability. Unfortunately, the significant energy loss resulting from its nonradiative recombination has become a major obstacle to further improvement of device performance. Here, a 2D/3D multidimensional structure formed spontaneously at room temperature is developed. The results reveal that the formed Ruddlesden–Popper 2D (n = 1) perovskite atop CsPbI3−xBrx plays an active role in mediating carrier transport, maintaining a long‐life charge separation state on the nanosecond time scale and promoting the efficiency of carrier injection into the hole transport layer, and thus enhances the hole extraction efficiency, which greatly reduces severe interfacial nonradiative charge recombination. In addition, the undercoordinated Pb2+ is effectively passivated, resulting in significantly reduced surface trap density and prolonged charge lifetime within the perovskite films. Consequently, the combination of the above increases the solar cell efficiency from 19.05% to 20.31%, with an open‐circuit voltage raised to 1.23 from 1.17 V, which corresponds to an energy loss reduction from 0.54 to 0.49 eV. Also, the optimized solar cells exhibit better long‐term and thermal stability.

Minimizing surface defect is vital to further improve power conversion efficiency (PCE) and stability of inorganic perovskite solar cells (PSCs). Herein, we designed a passivator trifluoroacetamidine (TFA) to suppress CsPbI 3À x Br x film defects. The amidine group of TFA can strongly chelate onto the perovskite surface to suppress the iodide vacancy, strengthened by additional hydrogen bonds. Moreover, three fluorine atoms allow strong intermolecular connection via intermolecular hydrogen bonds, thus constructing a robust shield against moisture. The TFA-treated PSCs exhibit remarkably suppressed recombination, yielding the record PCEs of 21.35 % and 17.21 % for 0.09 cm 2 and 1.0 cm 2 device areas, both of which are the highest for allinorganic PSCs so far. The device also achieves a PCE of 39.78 % under indoor illumination, the highest for allinorganic indoor photovoltaic devices. Furthermore, TFA greatly improves device ambient stability by preserving 93 % of the initial PCE after 960 h.