High detectivity ITO/organolead halide perovskite Schottky photodiodes

Schottky photodiodes, which are based on metal-semiconductor junctions, are one of the most widely used technologies for low cost image sensor arrays. Here, we fabricate a hole transport layer free organolead halide perovskite diode (ITO/CH3NH3PbI3/PCBM/BCP/Ag), and explore its Schottky diode behavior. A Schottky barrier is identified between the transparent conductor ITO and the solution processed perovskite (CH3NH3PbI3), with a barrier height of similar to 0.97 eV measured by capacitance-voltage (C-V) measurements. The Schottky barrier at the ITO/CH3NH3PbI3 junction is found to effectively suppress electron injection from ITO to the perovskite under reversed bias, leading to a surprising low dark current of 1.9 x 10(-9) A cm(-2) when biased at -0.1 V. When functioning as a photodetector, the ITO/CH3NH3PbI3 Schottky diode outperforms the conventional perovskite photodiode with PEDOT:PSS layer in terms of detectivity, reaching a high specific detectivity (D*) of 8.9 x 10(12) Jones. Moreover, by tuning the band gap of perovskite with the content of bromine (Br), i.e. CH3NH3Pb (I1-XBrX) 3(0 <= x <= 1), the Schottky barrier height at the ITO/perovskite junction is raised, further lowering the dark current of the perovskite photodiode. This work provides fundamental investigation on the device physics of the perovskite Schottky diode, as well as a low cost approach for designing the high sensitivity of photodetectors.