Schottky solar cell using few-layered transition metal dichalcogenides toward large-scale fabrication of semitransparent and flexible power generator

Toshiki Akama,Chao Li,Toshiaki Kato,Reito Nagai,Toshiro Kaneko,Wakana Okita

doi:10.1038/s41598-017-12287-6

Toshiki Akama, Chao Li + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-12287-6

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Journal: Scientific Reports	Publication Date: Sep 20, 2017
Citations: 66	License type: open-access

Affiliation: Tohoku University

Abstract

Few-layered transition metal dichalcogenides (TMDs) are known as true two-dimensional materials, with excellent semiconducting properties and strong light–matter interaction. Thus, TMDs are attractive materials for semitransparent and flexible solar cells for use in various applications. Hoewver, despite the recent progress, the development of a scalable method to fabricate semitransparent and flexible solar cells with mono- or few-layered TMDs remains a crucial challenge. Here, we show easy and scalable fabrication of a few-layered TMD solar cell using a Schottky-type configuration to obtain a power conversion efficiency (PCE) of approximately 0.7%, which is the highest value reported with few-layered TMDs. Clear power generation was also observed for a device fabricated on a large SiO2 and flexible substrate, demonstrating that our method has high potential for scalable production. In addition, systematic investigation revealed that the PCE and external quantum efficiency (EQE) strongly depended on the type of photogenerated excitons (A, B, and C) because of different carrier dynamics. Because high solar cell performance along with excellent scalability can be achieved through the proposed process, our fabrication method will contribute to accelerating the industrial use of TMDs as semitransparent and flexible solar cells.

Highlights

Transparent or semitransparent solar cells with excellent mechanical flexibility have attracted much attention as next-generation smart solar cells for various applications such as in the surfaces of windows, front display panels of personal computers and cell phones, and human skin[1,2,3]
The fabrication can be divided into two types: in one type, Transition metal dichalcogenides (TMDs) are used as power conversion efficiency (PCE) enhancers, wherein the TMDs are combined with other solar cell materials, such as Si and GaAs, where a relatively high PCE can be obtained even without TMD10–12
A Schottkytype solar cell was fabricated via mechanical exfoliation from bulk TMD crystals (WSe2 and WS2) and chemical vapor deposition (CVD)-grown WS2 combined with conventional photolithography and electron-beam lithography

Summary

Introduction

Transparent or semitransparent solar cells with excellent mechanical flexibility have attracted much attention as next-generation smart solar cells for various applications such as in the surfaces of windows, front display panels of personal computers and cell phones, and human skin[1,2,3]. Despite recent progress in the fabrication of solar cells[4,5], critical issues remain with regard to their practical applications, such as improving their power conversion efficiency (PCE), optical transparency, flexibility, stability, and scalability. Because most of these issues involve materials, the development of new photovoltaic materials with high transparency and mechanical flexibility is required. TMDs with thicknesses of less than 1 nm show strong light–matter interactions, affording absorption of incident sunlight of as much as 5–10%, which is one order of magnitude higher than that of common semiconductors such as GaAs and Si9 These features make TMDs among the most attractive materials for high-performance, semitransparent, and flexible solar cells. Despite having this technical advantage, a detailed study of solar cells containing mono- or few-layered TMDs has not yet been carried out; only one study on solar cells containing thick MoS2 (50 nm) has been reported[22]

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