Improved Perovskite Solar Cell Performance by High Growth Rate Spatial Atomic Layer Deposited Titanium Oxide Compact Layer

In this study, titanium dioxide (TiO2) films are prepared using spatial atomic layer deposition (sALD) as an additional compact layer of tin oxide (SnO2) electronic transport layer-based perovskite solar cells. The experimental results show that the deposition of sALD TiO2 films on the fluorine-doped tin oxide substrate improves the haze at mid-long wavelengths, compensating the optical loss caused by the absorption of the TiO2 layer in short-wavelengths. Compared to conventional cells, the insertion of the sALD TiO2 compact layer regardless the thickness shows significantly improved open-circuit voltage, indicating the enhanced hole blocking ability as evidenced by the reduced reverse saturation current. In addition, the change in TiO2 thickness is found to have impacts on short-circuit current, fill factor and hysteresis of the devices. The optimal sALD TiO2 thickness of 10 nm leads to the best cell conversion efficiency of 20.1%, approximately improved by 6% compared to that of the conventional cells. Compared to conventional ALD techniques and other methods, the sALD which does not require vacuum system has the pinhole-free, low-cost, very fast and simple processes, demonstrating the great potential of sALD films for applications in perovskite solar cells.