Self-Powered and Fast Response MoO<sub>3</sub>/n-Si Photodetectors on Flexible Silicon Substrates with Light-Trapping Structures
Yajun Xu, Honglie Shen, Yufang Li, Zhen Yue, Wei Zhang, Qichen Zhao, Zehui Wang
Abstract
Flexible photodetectors are considered to be extremely important flexible electronic components of the future. In this work, flexible silicon (F-Si) substrates with inverted pyramidal light-trapping structures were prepared by wet chemistry and metal-assisted etching. Due to the better ability of the light-trapping structure to capture light, the F-Si substrate was capable of absorbing more than 90% of visible light and can be in bending angles of over 180°. On the basis of F-Si substrates with light-trapping structures, self-powered MoO3/n-Si heterojunction flexible photodetectors (FPDs) were prepared to achieve high responsivity (0.696 A/W@980 nm), detectivity (1.59 × 1013 jones), and fast response (τr/τd of 5.35 μs/0.97 μs). The devices also showed effective photoresponse in the wavelength range from 405 to 980 nm. Moreover, the Si-based FPDs exhibited a favorable response to high-frequency light, with a response frequency of up to 100 kHz. The photocurrent of the device maintained more than 95% of the initial value after 200 bending cycles. In addition, Si-based FPDs are successfully applied to fingertip heartbeat tests for human health data extraction. The development of Si-based FPDs provides a path for flexible electronic devices.