Proceedings of International Conference Asia-Pacific Hybrid and Organic Photovoltaics (AP-HOPV17)
Publication date: 7th November 2016
Electron extraction layer (EEL) as one of the most important component in organometal–halide perovskites solar cells (PSCs) has attracted considerable research efforts on both materials and its interface with the light-harvesting perovskite. In this study, Ti-Fe-O ternary oxides were incorporated into the planar-structured PSCs based on CH3NH3PbI3 as the EELs compared with conventional TiOx compact layer and pure FeOx compact layer. It shows that for the Ti-Fe-O oxides, with the increase of the Fe content from 0%mol to 100%mol, the conductivities and energy levels of the thin films present relative changes. With the incorporation of Fe, the conduction bands get lower compared with pure TiOx which is proved by X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. Additionally, the conductivity is significantly improved according to the conductive atomic force microscopy (CAFM) and linear sweep voltammetry (LSV) measurement. As a result, the oxides with higher Fe content give better electron extractions according to the photoluminescence (PL) spectroscopies measured in both steady and transient state. On the contrary, more narrow energy gap due to higher Fe ratio would result in short-wavelength- light loss and lower open circuit voltage (VOC). Consequently, Ti0.5Fe0.5Ox with the optimal Ti-Fe ratio of 1:1 gives the highest power conversion efficiency (PCE) up to 14.7% higher than pure TiOx and FeOx with reasonable short circuit current (JSC), VOC and highly reduced hysteresis.