High-performing UV photodetectors by thermal-coupling transparent photovoltaics

Understanding of light-driven electric power (photovoltaics) and thermally–induced electric (pyroelectric) effect is crucial for the next-generation of optoelectronics, emphasizing sustainability and portability with improved performance. Herein, we report the high-performing thermal-coupling transparent photovoltaics for ultrafast photodetection. Optically transparent photovoltaic device has p–n heterojunction, with n-ZnO and two different p-type metal oxides (Cu2O or NiO). The ZnO based photodetector is highly transparent with average visible transmittance of 51%. Importantly, significant enhancement of device sensitivity toward ultraviolet (UV) light (λ = 365 nm) is obtained via tuning the pyroelectric effect of ZnO. The pyro-current is originated from polarization charges due to thermal variation, thus the control of heat flow in ZnO is the origin to enhance pyro-current. The lower thermal conductivity of Cu2O (4.5 W m−1 K−1) is more effective rather than the case of NiO to shape the well-confined heat in ZnO thermal reservoir, resulting in the significantly enhanced pyro-current (176.3%). The transparent ZnO/Cu2O photodetector exhibits the extremely-high responsivity of 0.98 A W−1 and detectivity of 1.62 × 1013 Jones, with μs response speed at zero bias condition due to the photovoltaic operation. This will bring the self-support transparent electronics for versatile see-through platforms without bulky power system. One day people will get information quickly and wireless without loss of vision.