Dr. Scott Warren "2D materials as building blocks for solar energy conversion"
Wednesday, September 16, 2015
1:30 pm - 3:00 pm
Hudson Hall 125
Converting sunlight into electrical or chemical energy is a profound challenge, with progress closely linked to improvements in semiconductor design. Two dimensional semiconductors could provide many advantages, with tunable band gaps, high mobility, and no intrinsic surface states. Here we describe our development of black phosphorus-an elemental form of phosphorus-as a new quantum-confined 2D material. We have invented a new method to measure the band gap and have made the first direct measurements of this important parameter, finding that it can be tuned from 0.3 eV in bulk black phosphorus to 2.3 eV in a monolayer. This degree of tunability -- which far exceeds other 2D materials and most quantum dots -- opens opportunities to use this material for solar energy conversion, particularly in pan-chromatic multi-junction solar cells. To that end, I will present two exciting developments from our laboratory: (1) a demonstration of how band gap engineering can be used in 2D black phosphorus to enhance solar-to-chemical energy conversion and (2) a discussion of how 2D black phosphorus can be re-assembled into an electrically conductive 3D material while remaining largely quantum-confined. Our experimental observations and the design rules that they illuminate should open a rich playground for innovative materials research, located squarely at the intersection of 2D materials and solar energy.