Self-powered broadband photodetector based on a solution-processed p-NiO/n-CdS:Al heterojunction

Abstract

Solution-processed photodetectors have emerged as the next generation of sensing technology owing to their ease of integration with electron devices and of tuning photodetector performance. Currently, novel self-powered photodetectors without an external power source, for use in sensing, imaging and communication, are in high demand. Herein, we successfully developed a self-powered photodetector based on a novel solution-processed p-NiO/n-CdS:Al heterojunction, which shows an excellent current rectification characteristic ratio of up to three orders in the dark and distinctive photovoltaic behavior under light illumination. The complete solution synthesis route followed the development of CdS:Al thin films on ITO substrates by chemical bath deposition and NiO thin films by the sol-gel route. Optical absorption data revealed that NiO is more active in the UV region and CdS:Al has a majority of absorption in the visible region; so, upon light illumination, the effective separation of photogenerated carriers produces fast photodetection in the UV–visible region. The photoresponsivity values of the fabricated device were calculated to be 55 mA W−1 and 30 mA W−1 for UV and visible illumination, respectively. Also, the device has a fast rise and decay photoresponse speed at zero bias voltage, due to the self-driven photovoltaic effect which makes this heterojunction a self-powered device. This complete solution and new method of fabrication make it possible to combine different materials and flexible substrates, enhancing its potential applications in photodetectors, optoelectronic devices and sensors.

Real-Time Ultraviolet Monitoring System with Low-Temperature Solution-Processed High-Transparent p–n Junction Photodiode with a Fast Responsive and High Rectification Ratio

“…Table and Table S1 show the recent performance data of solution-processed UV photodetectors based on p–n junctions and various photodetectors, comparing them with the PTAA/ZnO PD. Our device showcases exceptional characteristics, including high detectivity, rapid response time, and a superior rectification ratio compared to other UV photodetectors. − Moreover, the unencapsulated devices, stored at a relative humidity of approximately 45%, underwent periodic I – V curve measurements. After 60 days, Figure S12 shows no significant change observed in the electrical characteristics of the measured device.…”