High-Performance p–n Junction Transition Metal Dichalcogenide Photovoltaic Cells Enabled by MoO<sub><i>x</i></sub> Doping and Passivation
Koosha Nassiri Nazif, Aravindh Kumar, Jiho Hong, Nayeun Lee, Raisul Islam, Connor J. McClellan, Ouri Karni, Jorik van de Groep, Tony F. Heinz, Eric Pop, Mark L. Brongersma, Krishna C. Saraswat
Abstract
Layered semiconducting transition metal dichalcogenides (TMDs) are promising materials for high-specific-power photovoltaics due to their excellent optoelectronic properties. However, in practice, contacts to TMDs have poor charge carrier selectivity, while imperfect surfaces cause recombination, leading to a low open-circuit voltage (VOC) and therefore limited power conversion efficiency (PCE) in TMD photovoltaics. Here, we simultaneously address these fundamental issues with a simple MoOx (x ≈ 3) surface charge-transfer doping and passivation method, applying it to multilayer tungsten disulfide (WS2) Schottky-junction solar cells with initially near-zero VOC. Doping and passivation turn these into lateral p–n junction photovoltaic cells with a record VOC of 681 mV under AM 1.5G illumination, the highest among all p–n junction TMD solar cells with a practical design. The enhanced VOC also leads to record PCE in ultrathin (<90 nm) WS2 photovoltaics. This easily scalable doping and passivation scheme is expected to enable further advances in TMD electronics and optoelectronics.