High detectivity ITO/organolead halide perovskite Schottky photodiodes

Abstract

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/CH 3 NH 3 PbI 3 /PCBM/BCP/Ag), and explore its Schottky diode behavior. A Schottky barrier is identified between the transparent conductor ITO and the solution processed perovskite (CH 3 NH 3 PbI 3 ), with a barrier height of ∼0.97 eV measured by capacitance-voltage (C-V) measurements. The Schottky barrier at the ITO/CH 3 NH 3 PbI 3 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×10 −9 A cm −2 when biased at −0.1 V. When functioning as a photodetector, the ITO/CH 3 NH 3 PbI 3 Schottky diode outperforms the conventional perovskite photodiode with PEDOT:PSS layer in terms of detectivity, reaching a high specific detectivity (D * ) of 8.9×10 12 Jones. Moreover, by tuning the band gap of perovskite with the content of bromine (Br), i.e. CH 3 NH 3 Pb (I 1−X Br X ) 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.

Study of Metal–Semiconductor–Metal CH3NH3PbBr3 Perovskite Photodetectors Prepared by Inverse Temperature Crystallization Method

“…Sensors 2020, 20, x FOR PEER REVIEW 2 of 10 for a wide range of applications in the field of optoelectronics. Thus far, various types of light sensors have been studied and consequently applied; these include various photodetectors and Schottky barrier diodes [13][14][15][16][17][18][19][20][21][22][23][24][25]. Metal-semiconductor-metal (MSM) structured light sensors or photodetectors have the advantages of a straightforward manufacturing process, high sensitivity, and high response speed as compared with sensors possessing other structures.…”

Low‐Dimensional Contact Layers for Enhanced Perovskite Photodiodes

“…[ 22,23 ] Furthermore, fine‐tuned bromide ratios near the bottom interface have proven to be an effective strategy to regulate defects and the built‐in potential of perovskite devices. [ 24,25 ] Inspired by these observations, control of both defects and energy‐band alignments at the bottom interface have been implemented in perovskite solar cells by introducing a halide‐containing buffer material, [ 26–28 ] resulting in improved device performance. Yet, simultaneous improvements in both structural defects and energy‐band alignments have been rarely investigated in the perovskite photodiodes.…”

Flexible Perovskite and Organic Semiconductor Heterojunction Devices for Tunable Band-Selective Photodetection

“…One strategy that can employ perovskites with different band gaps into a single device is thus further expected. Among the several device structures of photodetectors, photodiodes have been developed in the field of band-selective detection due to their outstanding superiorities in photosensitivity, frequency response, and simple two-terminal operation. − Besides, organic semiconductors (OSCs) exhibit low-cost solution-processable fabrication, light weight, and mechanical flexibility. Therefore, photodiodes composed of perovskites and OSCs are promising to meet the above-mentioned requirements for band-selective detection.…”