Performance enhancement of perovskite/porous-Si photodetectors by reducing the dark current with concomitant use of graphene quantum dots in the active layer and bathocuproine on the back surface

Reduction of dark current (DC) in perovskite photodetectors (PDs) is one of the major issues to improve their functionalities. In this work, we employ graphene quantum dots (GQDs), porous Si (PSi), and bathocuproine (BCP) in MAPbI ₃-based PDs for enhancing the film crystallinity/photoresponse, the spectrum broadness/response speed, and the back-surface passivation/carrier blocking effect, respectively. The GQDs-added MAPbI ₃ (MAPbI ₃ :GQDs)/PSi/BCP PD exhibits a delta-function-like photocurrent (PC)/DC ratio-vs-voltage behavior with a maximum of about 10 ⁵, resulting from sharp reduction of the DC and the built-in potential profile at 0 V, meaning “self-powered”. Specific detectivity of the MAPbI ₃ :GQDs/PSi/BCP PD is almost 50 times larger than that of the counterpart without GQDs and BCP. The PD also shows a broadband photoresponse in the 380 – 950 nm range, where the responsivity (R) ≥ 0.2 AW ⁻¹, and decay time of 735 ns, extremely higher performance than the bulk-Si counterpart PD. The PD maintains 73 or 65% of its original PC even after 2000 h under 600-nm (600 μWcm ⁻²) or 1-sun (100 mWcm ⁻²) illumination, respectively, indicating remarkable stability.