Pronounced photovoltaic response from multi-layered transition-metal dichalcogenides PN-junctions

TL;DR

This study demonstrates that multi-layered transition-metal dichalcogenides PN-junctions exhibit a pronounced photovoltaic response with efficiencies exceeding 14%, highlighting their potential for solar energy applications.

Contribution

The paper provides experimental evidence of high photovoltaic efficiency in multi-layered TMD PN-junctions, surpassing previous results from bulk or monolayer TMDs.

Findings

Photovoltaic efficiency exceeds 14% under AM-1.5 illumination.

PN-junctions show diode-like response with ~70% fill-factor.

Potential for further efficiency improvements through gap tuning and contact optimization.

Abstract

Transition metal dichalcogenides (TMDs) are layered semiconductors with indirect band gaps comparable to Si. These compounds can be grown in large area, while their gap(s) can be tuned by changing their chemical composition or by applying a gate voltage. The experimental evidence collected so far, points towards a strong interaction with light, which contrasts with the small photovoltaic efficiencies $\eta \geq 1$ % extracted from bulk crystals or exfoliated monolayers. Here, we evaluate the potential of these compounds by studying the photovoltaic response of electrostatically generated PN-junctions composed of approximately ten atomic-layers of MoSe$_2$ stacked onto the dielectric $h$-BN. In addition to ideal diode-like response, we find that these junctions can yield, under AM-1.5 illumination, photovoltaic efficiencies $\eta$ exceeding 14 %, with fill-factors of ~ 70 %. Given the available strategies for increasing $\eta$ such as gap tuning, improving the quality of the electrical contacts, or the fabrication of tandem cells, our study suggests a remarkable potential for photovoltaic applications based on TMDs.