Transparent neutral-colored CsPbBr 3 perovskite solar cell with biological soybean lecithin food additives

Abstract We report the first perovskite solar cell incorporating soybean lecithin, a biological plant-based food additive. When added in small concentration to perovskite precursor inks, it helps to obtain compact and uniform CsPbBr 3 thin films. Our devices exhibit very high average visible transmittances (AVTs) (>70%), color rendering index (CRI) up to 84% and neutrality (CIE coordinates of 0.38, 0.39). The addition of lecithin almost doubled power conversion efficiency from 0.84% to 1.52%. Such high transparency, although limiting their overall efficiency, can be used in environments where transparency and color neutrality are important features, such as windows, facades, lens in smart glasses, and greenhouses. The transparency-efficiency profile fits the trend in performance of emerging photovoltaic devices, with amongst the highest voltages reported at these transmittances. Furthermore, the stability in ambient air also improved with addition of lecithin, losing only 25% of efficiency after 1 year versus 50% for devices with no lecithin.