Prof Henry Snaith FRS

Abstract:

Further improvements in perovskite solar cells require better control of ionic defects in the perovskite photoactive layer during the manufacturing stage and their usage. Here we report a living passivation strategy using a hindered urea/thiocarbamate bond Lewis acid–base material (HUBLA), where dynamic covalent bonds with water and heat-activated characteristics can dynamically heal the perovskite to ensure device performance and stability. Upon exposure to moisture or heat, HUBLA generates new agents and further passivates defects in the perovskite. This passivation strategy achieved high-performance devices with a power conversion efficiency (PCE) of 25.1 per cent. HUBLA devices retained 94 per cent of their initial PCE for approximately 1,500 hours of ageing at 85 degrees Celsius in nitrogen and maintained 88 per cent of their initial PCE after 1,000 hours of ageing at 85 degrees Celsius and 30 per cent relative humidity in air.

Abstract:

Demand for energy in the context of climate change is driving rapid deployment of low-cost renewable energy and is accelerating efforts to deliver advanced photovoltaic (PV) technologies. In the past decade, the steeply rising solar-to-electrical power conversion efficiency of metal-halide perovskite solar cells (PSCs) make them a compelling candidate for next-generation PVs, with interesting applications envisaged beyond traditional solar plants. These include building integrated PVs, flexible solar-powered electronics, and solar vehicles and aircraft. Metal-halide perovskites benefit from the low formation energy for crystallization, a consequence of their ionic nature, which enables close to ambient-temperature solution or vapor-phase deposition and a thin-film crystallization process. However, the ease by which rapid crystallization occurs also introduces defects and local heterogeneities throughout the perovskite films and at internal interfaces, which limits their efficiency (1).