Eco-friendly ultrafast self-powered p-Si/n-ZnO photodetector enhanced by photovoltaic-pyroelectric coupling effect

An energy harvester can operate as a self-powered sensor to convert ambient solar and thermal energies into electrical signals. Here, a hybrid self-powered sensor to convert incident light energy and light-induced temperature fluctuation into electrical signals is reported based on p-Si/n-ZnO heterojunction. The device showed high photo-to-dark current ratio of 6.5 × 10³ and 1.07 × 10⁴ upon illumination with UV (365 nm) and NIR (850 nm) lights, respectively. Additionally, the device revealed conspicuous light-induced pyroelectric voltage signals, increased from 8.26 to 20.38 mV and from 15.4 to 26.70 mV upon increasing UV and NIR light intensities from 1.75 to 3.88 and from 0.33 to 1.04 mW/cm², respectively. The response time was enhanced from 361 to 78 μs at the rising edge and from 242 to 152 μs at the falling edge owing to the photovoltaic-pyroelectric coupling effect. The self-powered device was capable to follow high-frequency (10 kHz) optical pulses, showing an ultrafast rise time of 9.8 μs. The photovoltaic-pyroelectric coupling effect opens a new avenue for multifunctional eco-friendly self-powered sensors compatible with next generation technology.