These authors contributed equally to this work. SUMMARYThe plant family 1 UDP-glycosyltransferases (UGTs) are the biggest GT family in plants, which are responsible for transferring sugar moieties onto a variety of small molecules, and control many metabolic processes; however, their physiological significance in planta is largely unknown. Here, we revealed that two Arabidopsis glycosyltransferase genes, UGT79B2 and UGT79B3, could be strongly induced by various abiotic stresses, including cold, salt and drought stresses. Overexpression of UGT79B2/B3 significantly enhanced plant tolerance to low temperatures as well as drought and salt stresses, whereas the ugt79b2/b3 double mutants generated by RNAi (RNA interference) and CRISPR-Cas9 strategies were more susceptible to adverse conditions. Interestingly, the expression of UGT79B2 and UGT79B3 is directly controlled by CBF1 (CRT/DRE-binding factor 1, also named DREB1B) in response to low temperatures. Furthermore, we identified the enzyme activities of UGT79B2/B3 in adding UDP-rhamnose to cyanidin and cyanidin 3-O-glucoside. Ectopic expression of UGT79B2/B3 significantly increased the anthocyanin accumulation, and enhanced the antioxidant activity in coping with abiotic stresses, whereas the ugt79b2/b3 double mutants showed reduced anthocyanin levels. When overexpressing UGT79B2/B3 in tt18 (transparent testa 18), a mutant that cannot synthesize anthocyanins, both genes fail to improve plant adaptation to stress. Taken together, we demonstrate that UGT79B2 and UGT79B3, identified as anthocyanin rhamnosyltransferases, are regulated by CBF1 and confer abiotic stress tolerance via modulating anthocyanin accumulation.

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Hole transfer material (HTM)‐free, carbon‐based all‐inorganic perovskite solar cells (C‐PSCs) are promising alternatives to conventional organic–inorganic hybrid PSCs in addressing thermal and moisture instability issues. However, the energy level mismatch between the inorganic perovskite and carbon electrode coupled, together with the incapability of the carbon electrode to reflect incident light for reabsorption, limits the power conversion efficiency (PCE) of C‐PSCs. To address these issues, herein, a new strategy of a hexyltrimethylammonium bromide (HTAB)‐modified CsPbI2Br perovskite surface is devised to reduce this energy offset from 0.70 to 0.32 eV and increase the built‐in potential by 70 mV for the final devices. Additionally, a CsPbI2Br perovskite film with a thickness of up to 800 nm is realized via a hot‐flow‐assisted spin coating approach in an ambient atmosphere with humidity of less than 80%. Reduced energy offset coupled with suppressed charge recombination and thick perovskite layer boosts the champion PCE of CsPbI2Br C‐PSCs to 14.3% (Jsc = 14.1 mA cm−2, Voc = 1.26 V, and fill factor = 0.806), and the average PCE to 13.9% under one sun illumination. A new certified efficiency record of 14.0% is obtained for HTM‐free inorganic C‐PSCs. Meanwhile, the moisture‐resistant barrier from the alkyl chain in HTAB improves the stability of the final devices.

All‐inorganic CsPbI3 quantum dots (QDs) have shown great potential in photovoltaic applications. However, their performance has been limited by defects and phase stability. Herein, an anion/cation synergy strategy to improve the structural stability of CsPbI3 QDs and reduce the pivotal iodine vacancy (VI) defect states is proposed. The Zn‐doped CsPbI3 (Zn:CsPbI3) QDs have been successfully synthesized employing ZnI2 as the dopant to provide Zn2+ and extra I−. Theoretical calculations and experimental results demonstrate that the Zn:CsPbI3 QDs show better thermodynamic stability and higher photoluminescence quantum yield (PLQY) compared to the pristine CsPbI3 QDs. The doping of Zn in CsPbI3 QDs increases the formation energy and Goldschmidt tolerance factor, thereby improving the thermodynamic stability. The additional I− helps to reduce the VI defects during the synthesis of CsPbI3 QDs, resulting in the higher PLQY. More importantly, the synergistic effect of Zn2+ and I− in CsPbI3 QDs can prevent the iodine loss during the fabrication of CsPbI3 QD film, inhibiting the formation of new VI defect states in the construction of solar cells. Consequently, the anion/cation synergy strategy affords the CsPbI3 quantum dot solar cells (QDSC) a power conversion efficiency over 16%, which is among the best efficiencies for perovskite QDSCs.