Comparative studies on transport layer-free perovskite Co-doped MAPbI3 photodetectors prepared on ITO and FTO substrates

Lead halide perovskites (LHPs) have shown to be important candidates for fabricating efficient photodetectors (PDs). Recently, remarkable photodetection have been observed in transport layer-free LHP PDs prepared on various transparent conductive layers (TCLs). Herein, comparative studies on performance of transport layer-free Co-doped MAPbI 3 thin film PDs prepared on typical TCLs including indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) substrates have been reported. Structural investigations showed that ITO substrates facilitated the growth of improved Co doped MAPbI 3 thin films with a decreased density of boundary defects, which have been attributed to the relaxation of strains in crystalline grains caused by the compensation effect of strains between the Co doping (∼ 5.8 at% relative to Pb) and interfacial lattice mismatch at the MAPbI 3 /ITO interface. In addition, optical studies have evidenced an improved carrier transportation at MAPbI 3 /ITO interface. Collectively, transport layer-free MAPbI 3 /ITO PDs showed an improved performance in terms of reduced dark current and increased photocurrent simultaneously. As a result, ITO substrates have proven to be an important platform for fabricating efficient transport layer-free MAPbI 3 thin film PDs.