Optoelectrical Performance Enhancement by Integrating CsPbI₃ Quantum Dots Layer with Bi₂O₂Se/Si Photodiodes

Abstract Benefiting from the versatile energy band structure design of 2D materials and effective modulation of dopant concentration in Si, 2D/Si hybrid heterostructures demonstrate desirable device performances. Bismuth oxychalcogenide material Bi 2 O 2 Se, exhibits high carrier mobility and ultrafast optoelectrical dynamics, when interfaced with Si, the device efficiencies will be improved in the aspects of photo‐induced carrier separation and collection. However, due to the indirect bandgap features of Bi 2 O 2 Se and Si, the light absorption of the heterostructure is unsatisfactory, deteriorating the external quantum efficiency. To address this, additional light absorption enhancing materials (LAEMs) are incorporated, and boosted with the photo‐gating effects generated from the residual carriers within the LAEMs, and photoconductive gain and photoresponsivity are improved at the cost of response speed. In this study, the CsPbI 3 quantum dot layer is adopted to provide excess carriers, which are injected into Bi 2 O 2 Se/p‐Si heterojunction in the form of excitonic energy transfer. The carrier multiplication effect is thus circumvented, leading to an improved photoresponsivity as high as 2078 A W −1 , while specific time constants of the rising and falling edges of photocurrent are accelerated to 267 and 391 µs.