Flexible transparent photovoltaics for ultra-UV photodetection and functional UV-shielding based on Ga2O3/Cu2O heterojunction

Ultraviolet (UV) radiation, the harmful portion of the solar spectrum, can have chronic effects on human skin and eyes. Long and periodic exposure to UV radiation can cause skin cancers such as basal and squamous cell carcinoma and visual impairment due to corneal damage. Blocking UV radiation and utilizing the corresponding high energy for energy production can lead to breakthroughs in the medical field and the energy production crisis. Although metal oxide-based photovoltaics are used to harvest UV radiation, their rigid design, high-temperature fabrication, and high weight make them unsuitable for wearable and portable applications. However, developing a lightweight, flexible solar cell based on earth-abundant and nontoxic inorganic materials is still a challenge. In this work, we develop a completely inorganic, lightweight, highly robust, flexible, and transparent Ga2O3/Cu2O heterojunction for photovoltaics and photodetectors. The flexible Ga2O3/Cu2O heterojunction blocked almost 96% of UV light and produced a power of 156 µW/cm2. The device also showed UV-Vis photodetection along with high robustness and durability even after a large number of bending cycles. The device can be easily integrated on sites for UV blocking and energy production and provides a high degree of freedom of installation on windows or surfaces of objects (automobiles, buildings, etc.) to power the Internet of Things (IoT) systems.