Flexible and Transparent Ga 2 O 3 /NiO Photovoltaic Diode for Full‐Wave Rectification in Wearable Optoelectronics
Sourov Hossain, Sanh Vo Thi, Md Arifur Rahman Barno, Seunghee Cho, Vivek Mohan More, Malkeshkumar Patel, Kibum Lee, Joondong KimABSTRACT
Flexible and transparent electronic components are critical for next‐generation wearable optoelectronic devices, which require lightweight, flexible, and optically transparent power solutions. Wearable systems, including smart textiles, flexible displays, and bioelectronics, commonly operate using direct current (DC). While transparent photovoltaics can directly generate DC power under illumination, triboelectric and piezoelectric nanogenerators produce alternating current (AC), requiring efficient AC‐to‐DC conversion for practical use. However, conventional silicon‐based rectifiers are unsuitable for flexible transparent electronics because of their rigidity and opacity. This study presents a flexible and transparent Ga 2 O 3 /NiO heterojunction photovoltaic diode array functioning as a full‐wave rectifier for wearable optoelectronic applications. The sputter‐deposited device exhibits 65% optical transparency in the visible region, a low leakage current of 1.07 nA, and a rectification ratio of 8.505 × 10 3 at ± 2 V. Under ultraviolet‐C (UVC) illumination, the device demonstrates photovoltaic energy harvesting with an open‐circuit voltage of 462 mV and a short‐circuit current density of 103.08 µA cm −2 . It also shows self‐powered photodetection performance with a responsivity of 13 mA W −1 and a detectivity of 2.43 × 10 11 Jones. Integration into a full‐wave rectifier successfully enables AC‐to‐DC conversion, highlighting its potential for transparent, flexible, and self‐powered wearable devices.