2, Institute of Physics and Astronomy, Potsdam-Golm, Brandenburg, Germany
Rapid progress has been achieved in improving the power conversion efficiency (PCE) of organohalide perovskite solar cells (PVSCs), which have now reached 22.1%. Engineering the interlayers between the junction and electrodes has enabled enhancement of charge extraction efficiency and open-circuit voltage (Voc), and reduction of device hysteresis. Herein, a simple oxygen plasma treatment is reported and used to change the surface energy and work function of “hydrophobic” organic semiconductor interlayers for perovskite solar cells. The UV-ozone treatment was also found to increase the semiconductor conductivity, which can lead to more efficient hole extraction. In this presentation, we report the effect of an oxygen plasma treatment on the surface energy, work function and device performance of four different p-type interlayers. After the plasma treatment, the “hydrophobic” surfaces of the different p-type polymers were found to have changed to “hydrophilic” and the ionisation potential (IP) increased to be closer to the IP of the perovskite active layer. Finally, the performance of inverted MAPbI3 perovskite devices with treated interlayers will be discussed. The best perovskite solar cells were found to have a Voc of 1.05 V, FF of 0.80, Jsc of 22.7 mA/cm2 and PCE of 19%.