Impact of drying temperature on the photovoltaic performance and impedance spectra of hole transport material free air processed perovskite solar cells

Due to the rapid increase in power conversion efficiency (PCE) of organic–inorganic perovskite solar cells (PSCs) and exceeding the PCE achieved in conventional single-junction silicon solar cells this technology has become the focus of research. The quality of perovskite film plays a vital role in developing the high performance PSCs and depends upon many factors, such as, composition of the perovskite, growth method, drying temperature, etc. In this work, hole transport material free (HTM-free) glass/FTO/c-TiO2/m-TiO2/m-ZrO2/Carbon electrode based PSCs are fabricated. Effect of prevoskite drying temperature on the photovoltaic performance and impedance spectra of these devices is studied by varying temperature from 50 to 70 °C. The photovoltaic and impedance spectra of the devices are observed to be highly dependent on the drying temperature. The best power conversion efficiency is obtained for drying temperature of 60 °C. These results show that determining the optimum drying temperature is crucial to ensure formation of perovskite crystals, highest surface coverage of perovskite, highest light harvesting and successful charge extraction from the fabricated devices in order to achieve highest performance.