Engineering Chemically Exfoliated Large-Area Two-Dimensional MoS2 Nanolayers with Porphyrins for Improved Light Harvesting

• Published in: Chemphyschem Vol. 17; no. 18; pp. 2854 - 2862
• Main Authors: Zhang, Hanyu, Choi, Jungwook, Ramani, Arjun, Voiry, Damien, Natoli, Sean N., Chhowalla, Manish, McMillin, David R., Choi, Jong Hyun
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 19.09.2016; Wiley Subscription Services, Inc
• Subjects: light harvesting; molybdenum disulfide; nanolayers; photocurrent; porphyrins; Zinc; molybdenum disulfide; light harvesting; nanolayers; photocurrent; porphyrins
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201600511

Molybdenum disulfide (MoS2) is a promising candidate for electronic and optoelectronic applications. However, its application in light harvesting has been limited in part due to crystal defects, often related to small crystallite sizes, which diminish charge separation and transfer. Here we demonstrate a surface‐engineering strategy for 2D MoS2 to improve its photoelectrochemical properties. Chemically exfoliated large‐area MoS2 thin films were interfaced with eight molecules from three porphyrin families: zinc(II)‐, gallium(III)‐, iron(III)‐centered, and metal‐free protoporphyrin IX (ZnPP, GaPP, FePP, H2PP); metal‐free and zinc(II) tetra‐(N‐methyl‐4‐pyridyl)porphyrin (H2T4, ZnT4); and metal‐free and zinc(II) tetraphenylporphyrin (H2TPP, ZnTPP). We found that the photocurrents from MoS2 films under visible‐light illumination are strongly dependent on the interfacial molecules and that the photocurrent enhancement is closely correlated with the highest occupied molecular orbital (HOMO) levels of the porphyrins, which suppress the recombination of electron–hole pairs in the photoexcited MoS2 films. A maximum tenfold increase was observed for MoS2 functionalized with ZnPP compared with pristine MoS2 films, whereas ZnT4‐functionalized MoS2 demonstrated small increases in photocurrent. The application of bias voltage on MoS2 films can further promote photocurrent enhancements and control current directions. Our results suggest a facile route to render 2D MoS2 films useful for potential high‐performance light‐harvesting applications. Layer by layer: Modulation of the photoelectrochemical properties of MoS2 nanolayers is achieved by interfacial engineering with an array of porphyrin molecules. A maximum tenfold increase in photocurrent is observed for MoS2 with Zn‐centered protoporphyrins. A unique modulation of photoelectrochemical properties of 2D semiconductors and a fundamental understanding of photoinduced charge transfer for MoS2‐based light harvesting is presented.