Jian Cui

Abstract With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2‐difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb 2+ and passivate under‐coordinated Pb 2+ defects. Consequently, the perovskite crystallization rate is reduced and high‐quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL to improve its carrier mobility. With the help of the combined effects of these groups in DFPDA, the PSCs with DFPDA additive achieve a champion efficiency of 22.21% and a substantially improved stability against moisture, heat, and light.

Abstract Water corrosion and dendrite growth seriously break the zinc plating/stripping process at the electrolyte/anode interface, causing the instability of the zinc metal anode of aqueous zinc batteries. Herein, a self‐consistent hydrophobic interface and orderly channels are assembled by three quaternary ammonium cationic surfactants, which can block the water erosion. Of particular interest, experimental results combined with theoretical calculation (DFT) reveals that the hydrophobic groups in quaternary ammonium cations are the determinaning factor in the kinetic process of zinc ion deposition and the life of the zinc anode. The massive micelles formed by benzyldimethyldodecylammonium with dodecyl and benzyl groups cause great hindrance to the transport and deposition of zinc ions. And dodecyltrimethylammonium with only a main hydrophobic group of dodecyl results in the higher polarization overpotential or voltage hysteresis for the zinc plating and lower coulombic efficiency (CE) < 99%. Surprisingly, the hydrophobic interface assembled by benzyltrimethylammonium (TMBA + ) with a main benzyl group can inhibit side reactions and regulate zinc uniform deposition. And the batteries based on TMBA + can achieve superb cycle stability with low voltage hysteresis and almost 100% CE. The proposed hydrophobic interface formed by quaternary ammonium cationic surfactants establishes pioneering work on zinc anode stability for zinc batteries and beyond.

Single-phase ZnCdO alloys with a band gap extending from the violet to yellow spectral range are fabricated by molecular beam epitaxy using extremely low growth temperatures in conjunction with O-rich growth conditions. The Cd concentration can be systematically adjusted via the Cd∕Zn beam pressure ratio. Despite growth temperatures as low as 150°C, layer-by-layer growth is accomplished allowing for the preparation of ZnCdO∕ZnO quantum well structures. Both epilayers and quantum wells exhibit strong band-gap-related emission at room temperature in the whole composition range.

under a 10 V bias, the highest reported for any perovskite material. The method provides a convenient strategy for producing large perovskite wafers with good optoelectronic properties, which will facilitate the development of large perovskite devices.