Effects of Cu, K and Guanidinium Addition to CH3NH3PbI3 Perovskite Solar Cells.

In this study, CH₃NH₃PbI₃ perovskite solar cells with added copper (Cu) and potassium (K) or guanidinium (GA) were fabricated and characterized. The effects of the additives on the photovoltaic properties, morphology and crystalline structure were investigated, and the electronic structures and thermodynamic stabilities are discussed. The stability and conversion efficiency of the perovskite solar cell improved by incorporating Cu at the lead site and K or GA at the CH₃NH₃ organic cation site in the cubic crystal. Simultaneous addition of Cu and K to the perovskite crystal suppressed decomposition of the crystal by desorption of methylammonium (MA), which led to improvement of the stability of the photovoltaic device. After 28 days, the conversion efficiency of the device with co-added Cu and K was still 10.8%, whereas that of the standard device decreased to 10.1%. [ABSTRACT FROM AUTHOR]