Our new paper titled “Ultra-low Dark Currents in Avalanche Amorphous Selenium Photodetectors using Solution-processed Quantum Dot Blocking Layer” was published in ACS Photonics.
In this paper, we propose a true solid-state alternative to the vacuum photomultiplier tube using amorphous selenium as the bulk avalanche i-layer. To achieve reliable and repeatable impact ionization gain without irreversible breakdown, a non-insulating metal oxide n-type hole-blocking/electron-transporting layer is needed. For the first time, we have deposited a solution-processed quantum dot (QD) hole blocking layer over an a-Se photoconductor at room temperature, without any surface or bulk crystallization. We have measured the lowest dark current density ever reported (30 pA/cm² at the onset of avalanche) compared to any other solid-state avalanche sensor at room temperature. Our results provide new strategies for the development of advanced solid-state photomultipliers via efficient QD-based interface layers to fully exploit the deterministic avalanche properties of a-Se.