Fabry-Perot interference and piezo-phototronic effect enhanced flexible MoS2 photodetector

Flexible photodetectors (PDs) are indispensable components for next-generation wearable electronics. Recently, two-dimensional (2D) materials have been implemented as functional flexible optoelectronic devices due to their characteristics of atomically thin layers, excellent flexibility, and strain sensitivity. In this work, we developed a flexible photodetector based on MoS2/NiO heterojunction, and Fabry-Perot (F-P) and piezo-phototronic effect have been employed to enhance the responsivity (R) and external quantum efficiency (EQE) of the devices. The F-P effect is utilized to improve the optical absorption of the MoS2, resulting in an enhancement in the photoluminescence (PL) of monolayer MoS2 and the EQE of the photodetector by 30 and 130 times, respectively. The flexible photodetector exhibits an ultrahigh detectivity (D*) of 2.6 x 1,0(14) Jones, which is the highest value ever reported for flexible MoS2 PDs. The piezo-potential of monolayer MoS 2 decreases the valence band offset at the interface of MoS2/NiO, which increases the transfer efficiency of the photon-generated carriers significantly. Under 1.17% tensile strain, the R of the flexible photodetector can be enhanced by 271%. This research may provide a universal strategy for the design and performance optimization of 2D materials heterostructures for flexible optoelectronics.