Photodetectors go 2-D

Abstract

Inside cameras and solar panels, photodetectors absorb light and convert it to useful electronic signals. How well these devices perform depends on how efficiently the detectors can turn incident photons into electrons and corresponding positively charged species called holes. These electron-hole (e-h) pairs can then move through the material to generate electricity. One way to improve this efficiency is to shrink the materials down to the nanoscale. Scientists have used quantum dots, carbon nanotubes, and graphene to achieve efficiencies beyond 100%, meaning a single photon produces more than one e-h pair, an effect known as e-h pair multiplication. Researchers at the University of California, Riverside, led by Nathaniel M. Gabor, now report greater than 300% efficiency with a class of ultrathin two-dimensional materials called transition-metal dichalcogenides. The photodetector is made of two atomic layers of WSe2 stacked on a single layer of MoSe2 (Nat. Nanotechnol. 2017, DOI: 10.1038/nnano.2017.203). ...