Improvement on Cs2AgBiBr6 perovskite photodetector by using ZnO/SnO2 double electron transport layer

Abstract

Recently, halide perovskites have attracted tremendous attention because of their great abilities in optoelectronic device. Lead-free double perovskite Cs2AgBiBr6 has recognized a promising optoelectronic material due to its photoelectric properties, low toxicity and stability. In perovskite photodetector, electron transport layer (ETL) plays an important role in device performance since their excellent electron extracting and transporting properties. The ETL can modify the interface and minimize the charge recombination in perovskite photovoltaic devices leading higher performance in photoelectronic application. Here, I demonstrated a high performance Cs2AgBiBr6 photodetector with double electron transport layer of ZnO nanorods/ SnO2. The device showed high performance with the responsivity of 0.89 AW-1, on/off ratio of 2.70 and response time of 1.69s. It is found that our device incorporating ZnO/SnO2 double ETL enhanced the responsivity, response speed, on/off ratio and dark current compare to that of the device with SnO2 ETL which is related to better band matching of the ZnO/SnO2 double ETL and Cs2AgBiBr6 and low charge recombination rate between the double ETL layer and perovskite surface. Compare to the SnO2 ETL-based Cs2AgBiBr6 photodetector, the responsivity enhanced 296%, showed 3.95 times faster rise time and 1.72 times faster decay time under the 365nm UV light. The double ETF not only solve the problem of ZnO and perovskite surface degradation but also improve the charge extracting and transferring ability of the device. The result indicate that the ZnO/SnO2 double electron transport layer is more suitable for Cs2AgBiBr6-based double perovskite photodetector. This kind of double ETL also provide a possible choice for other perovskite-based photoelectronic application in electron transport layer.