Self-Powered and Fast Response MoO₃/n-Si Photodetectors on Flexible Silicon Substrates with Light-Trapping Structures

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.

Flexible optoelectronic sensors: status and prospects

“…We further compared the performance of photodetectors with the same material on rigid and flexible substrates to discuss the limit in flexible fabrication of planar devices. As shown in Table 2, conventional bulk/thin film materials (i.e., Si 91 and InGaAs 92 ) that were thinned/exfoliated for flexible application showed decreased performance (reduced I dark and t rise ). It could be mainly due to the increase in surface defects upon thinning/exfoliation, as the defects are closer to the junction.…”

“…As shown in Table 2, conventional bulk/thin film materials ( i.e. , Si 91 and InGaAs 92 ) that were thinned/exfoliated for flexible application showed decreased performance (reduced I dark and τ rise ). It could be mainly due to the increase in surface defects upon thinning/exfoliation, as the defects are closer to the junction.…”

Self-driven broadband photodetectors on flexible silicon nanowires substrate by forming a heterojunction with reduced graphene oxide

“…Most flexible substrates are polymer-based, while offering flexibility, and suffer from limited thermal resistance and insulating properties. 18 Consequently, flexible semiconductor photodetectors, such as those employing silicon substrates, have been engineered to overcome these limitations and broaden the scope of flexible photodetection. [19][20][21][22] Since the polished surfaces of planar silicon wafers exhibit limited light capture capabilities, the inherent smoothness of these wafers hinders their proficiency in efficiently harnessing incident light, prompting the exploration of alternative strategies to enhance the lightcapturing performance.…”

Multilayered PdTe2/thin Si heterostructures as self-powered flexible photodetectors with heart rate monitoring ability

“…Nevertheless, although significant achievements have been gained, the exploration of flexible photodetectors based on group-10 TMD/semiconductor heterostructures are thus far scarcely reported. Meanwhile, the development of flexible and wearable health monitoring devices is becoming increasingly important nowadays due to deterioration of the environment and increasing number of human diseases worldwide [30,31] .…”