Rapid Conversion from Carbohydrates to Large-Scale Carbon Quantum Dots for All-Weather Solar Cells

A great challenge for state-of-the-art solar cells is to generate electricity in all weather. We present here the rapid conversion of carbon quantum dots (CQDs) from carbohydrates (including glucose, maltol, sucrose) for an all-weather solar cell, which comprises a CQD-sensitized mesoscopic titanium dioxide/long-persistence phosphor (<i>m</i>-TiO₂/LPP) photoanode, a I^–/I₃^– redox electrolyte, and a platinum counter electrode. In virtue of the light storing and luminescent behaviors of LPP phosphors, the generated all-weather solar cells can not only convert sunlight into electricity on sunny days but persistently realize electricity output in all dark–light conditions. The maximized photoelectric conversion efficiency is as high as 15.1% for so-called all-weather CQD solar cells in dark conditions

A Universal Grain “Cage” to Suppress Halide Segregation of Mixed-Halide Inorganic Perovskite Solar Cells

Bandgap-tunable mixed-halide perovskites offer exciting opportunities to construct efficient multijunction tandem solar cells. However, the ion migration always causes halide segregation, which inevitably creates detrimental defects and deteriorates the photovoltaic performances. Here, we report a universal caging strategy to suppress halide segregation by in situ formation of conjugated covalent organic frameworks (COFs) catalyzed by PbX2 (X = Br and I) during the formation of mixed-halide perovskite. Through theoretical calculation and systematic investigation, the strong electron-donating feature of COFs is shown to effectively solidify the soft lattice and impede the iodide ion transport from bulk to grain boundary, decelerating the light-induced halide-demixing process. Finally, the nonradiative recombination is significantly reduced, boosting efficiency up to 11.50% for an inorganic CsPbIBr2 perovskite solar cell and 14.35% for a CsPbI2Br cell with a prolonged shelf life and an improved photostability