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CsPbI3 perovskite is a promising light absorber in perovskite solar cells (PSCs) due to its suitable bandgap (Eg) and high chemical stability, but the perovskite phase is metastable in ambient atmosphere and prone to defect formation. To enhance phase stability and reduce defects, forming a low dimensional (LD) perovskite on CsPbI3 has proved effective. However, the energy levels for most of low‐conductivity LD perovskites are not very compatible with those of CsPbI3, which will impair charge separation and device performance. Herein, a new 1D perovskite (5‐Azaspiro[4.4]nonan‐5‐ium lead triiodide, ASNPbI3) with compatible energy levels and a large Eg is reported as a capping layer. The p‐type ASNPbI3 forms a p‐n heterojunction with n‐CsPbI3 with a staggered band alignment, considerably enhancing the carrier separation. Besides, by pre‐forming a ASNPbI3 at an intermediate stage, defects are suppressed in perovskite film. Consequently, the CsPbI3 PSCs based on carbon electrode without hole transporter (C‐PSCs) achieves a PCE of 18.34%, which is among the highest‐reported values for inorganic C‐PSCs. Furthermore, the hydrophobic ASNPbI3 capping layer has a high thermal stability that greatly enhances perovskite phase stability. Hence, the CsPbI3 C‐PSCs maintains 68% of its initial PCE after 400 h aging at 85°C in a N2 glovebox. [ABSTRACT FROM AUTHOR]

Precisely regulating surface reconstruction of copper (Cu) chalcogenides‐based catalysts to promote the multicarbon (C2+)selectivity of the electrochemical CO2 reduction reaction (CO2RR) is hampered by the challenging control of the intractable anions and the optimal Cuδ+ reduction (0 < δ < 1). Herein, a porous carbon‐supported copper selenides electrocatalyst that can remarkably improve the C2‐product yield and especially unveil the time‐revolved electrochemical CO2RR reconstruction process to enable the high C2‐selectivity, most notably for ethanol is constructed. The Faradic efficiency (FE) of C2‐products achieved is as high as ≈85.2% with a partial current density of 229.5 mA cm−2. Operando infrared spectroscopy and density functional theory (DFT) calculations unravel that the surface Se vacancies (VSe) formation brings closer the neighboring Cu+ atoms and activates the Cu sites, thereby rendering efficient generation of the key intermediates (*CO and *CHO) and lowering the C–C coupling barrier for C2 production. The appearance of metallic Cu can shorten the next‐nearest Cu0–Cu+ distance for O atom to bridge in, leading to the preferential formation of *OC2H4 towards ethanol instead of C–O bond cleavage to form ethylene. This work opens the avenue of designing suitable local atomic structures catalysts to engage the intermediates for targeted CO2RR products. [ABSTRACT FROM AUTHOR]

Post‐treatment is a widely used strategy to reduce defects in perovskite films, but has been largely limited to the solution phase. Herein, the posttreatment tool kit and develop a universal amine salts (AIXI) vapor healing strategy by taking advantage of the penetrating power of vapor and the soft‐matter characteristics of halide perovskite is expanded. In a striking demonstration, the post‐treatment of pristine perovskite layers allows simultaneous filling of the MA+ and I– vacancies, passivation of both the cation and anion defects, and healing of the films to high order and high crystallinity required for high device performance, from the surface to the bulk and all the way down to the bottom. Experiments and DFT calculations revealed that charge extraction can be enhanced and non‐radiative recombination can be reduced by regulating the energy levels and reducing the trap states via the AIXI vapor healing. Moreover, the diffusing AIXI can reach the NiOx surface to obstruct the undesirable interfacial reactions and passivate the interface defects, further reducing the open‐circuit voltage (Voc) loss. The vapor healing strategy substantially reduces the trap density from 4.76 × 1015 to 1.04 × 1015 cm–3, and promots power conversion efficiency of the champion device from 17.92% to 20.48% with superior device consistency, Voc up to 1.114 V and the operational device stability. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO2 to formate is believed to be one of the most promising technologies for producing clean fuels and valuable chemicals and for tackling the global warming problem. Herein, a novel synthesis strategy is presented for Bi‐based catalyst in CO2 reduction reaction (CO2RR). With the addition of acetic acid into the mother solution, heterostructured Bi/Bi2O3 nanoplates with abundant O vacancies (Bi/Bi2O3–Ov) and tailored coordination environments of the Bi ions are successfully synthesized, which exhibit excellent catalytic activity for CO2RR and high selectivity for formate generation with wide operable windows of pH (neutral to alkaline) and potential. In particular, the faradic efficiency (HCOOH) reaches ≥90% in a wide potential range of −0.7–−1.35 V versus reversible hydrogen electrode in neutral media, which dwarf most of the state‐of‐the‐art Bi‐based catalysts for CO2RR reported to date. Combined experimental and theoretical results show that the abundant O vacancies create frustrated Lewis pairs at the heterointerfaces with favorable adsorption characteristics, thereby facilitating the CO2RR process. This work opens up a new approach to promoting the catalytic activity and selectivity of Bi‐based materials for CO2RR by combining coordination and heterointerface engineering. [ABSTRACT FROM AUTHOR]