Mutual Photoluminescence Quenching and Photovoltaic Effect in Large-Area Single-Layer MoS2-Polymer Heterojunctions

TL;DR

This paper demonstrates a large-area MoS2-polymer heterojunction with high quantum efficiency and tunable photoluminescence, advancing the development of ultra-thin, efficient solar cells based on 2D materials.

Contribution

It presents the first large-area single-layer MoS2 heterojunction with organic polymer, achieving high quantum efficiency and tunable photoluminescence, providing new insights into recombination processes.

Findings

Quantum efficiency exceeds 40% in <20 nm thick cells.

Complete quenching of TMDS photoluminescence observed.

High current density per absorbing thickness achieved.

Abstract

Two-dimensional transition metal dichalcogenides (TMDCs) have recently attracted attention due to their superlative optical and electronic properties. In particular, their extraordinary optical absorption and semiconducting band gap have enabled demonstrations of photovoltaic response from heterostructures composed of TMDCs and other organic or inorganic materials. However, these early studies were limited to devices at the micrometer scale and/or failed to exploit the unique optical absorption properties of single-layer TMDCs. Here we present an experimental realization of a large-area type-II photovoltaic heterojunction using single-layer molybdenum disulfide (MoS2) as the primary absorber, by coupling it to the organic {\pi}-donor polymer PTB7. This TMDC-polymer heterojunction exhibits photoluminescence intensity that is tunable as a function of the thickness of the polymer layer, ultimately enabling complete quenching of the TMDC photoluminescence. The strong optical absorption in the TMDC-polymer heterojunction produces an internal quantum efficiency exceeding 40% for an overall cell thickness of less than 20 nm, resulting in exceptional current density per absorbing thickness in comparison to other organic and inorganic solar cells. Furthermore, this work provides new insight into the recombination processes in type-II TMDC-polymer heterojunctions and thus provides quantitative guidance to ongoing efforts to realize efficient TMDC-based solar cells.