Self-powered high-performance flexible GaN/ZnO heterostructure UV photodetectors with piezo-phototronic effect enhanced photoresponse

The quest and development of optoelectronic sensors with high performance, sustainable, wearable, portable, and maintenance-free operation offers a significant impetus to explore self-powered flexible photodetectors (PDs). Here, a p-GaN/n-ZnO heterostructure-based self-powered and flexible ultraviolet PD is demonstrated by combining laser lift-off of GaN film and hydrothermal synthesis of ZnO nanowires. The device shows a large on/off current ratio (up to 7.36 ×106), outstanding detection sensitivity (6.82 ×1013 Jones), and fast response (6.9/6.4 ms) at 325 nm illumination at a bias voltage of 0 V, also exhibiting a relatively broad spectral response, remarkable reproducibility under thousands of switching cycles, and superior mechanical stability. In addition, since both GaN and ZnO are piezoelectric semiconductor materials, the piezoelectric charges created at two sides of heterojunction interface under an external strain will regulate the separation, extraction and recombination of photo-generated carriers based on the piezo-phototronic effect, resulting in an enhancement of relative responsivity up to 22% with a compressive strain of − 0.48% under UV illumination of 38.4 mW/cm2. This work not only exhibits a self-powered flexible optoelectronic device with potential applications in photo-sensing for artificial skin, optical communication, and self-powered integrated systems, but also provides a strategy to optimize the performance of prospective optoelectronic sensors via the piezo-phototronic effect.