Hole transport free carbon-based high thermal stability CsPbI1.2Br1.8 solar cells with an amorphous InGaZnO4 electron transport layer

Due to their low cost, tunable band gap and excellent thermostability, all-inorganic halide perovskites CsPbX3 (X = Br, I) have become a kind of promising photovoltaic material. However, compared to the organic-inorganic hybrid perovskite solar cells, the performance of CsPbX3 solar cells still needs to be improved. In this work, for the first time, we applied the sol-gel derived amorphous InGaZnO4 film as electron transport layers (ETLs) in CsPbX3-based devices. In these devices, the carbon electrode deposited by screen printing replaced the unstable hole transport layer and the expensive metal electrode to obtain hole transport free carbon-based devices, which significantly simplifies the preparation process and reduces the production cost. With the application of amorphous InGaZnO4 films, devices show a relatively high power conversion efficiency (9.07%) and excellent thermal stability. Compared with the reported CsPbX3 devices using SnO2 or TiO2 ETLs, the performance of amorphous InGaZnO4 based devices has been significantly improved. This work provides a promising route to prepare highly thermally stable all-inorganic perovskite solar cells using a-IGZO films.