In Situ Growth of [hk1]‐Oriented Sb2S3 for Solution‐Processed Planar Heterojunction Solar Cell with 6.4% Efficiency

• Published in: Advanced functional materials Vol. 30; no. 35
• Main Authors: Jin, Xin, Fang, Yanan, Salim, Teddy, Feng, Minjun, Hadke, Shreyash, Leow, Shin Woei, Sum, Tze Chien, Wong, Lydia H.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.08.2020
• Subjects: [hk1] direction; Antimony; Antimony compounds; Crystal structure; Efficiency; Electron transport; Energy conversion efficiency; Heterojunctions; hydrothermal methods; Materials science; Orientation; Photovoltaic cells; Sb2S3; Solar cells; Thin films; Titanium dioxide; vertical growth
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202002887

Binary compound antimony sulfide (Sb2S3) with its nontoxic and earth‐abundant constituents, is a promising light‐harvesting material for stable and high efficiency thin film photovoltaics. The intrinsic quasi‐1D (Q1D) crystal structure of Sb2S3 is known to transfer photogenerated carriers rapidly along the [hk1] orientation. However, producing Sb2S3 devices with precise control of [hk1] orientation is challenging and unfavorable crystal orientations of Sb2S3 result in severe interface and bulk recombination losses. Herein, in situ vertical growth of Sb2S3 on top of ultrathin TiO2/CdS as the electron transport layer (ETL) by a solution method is demonstrated. The planar heterojunction solar cell using [hk1]‐oriented Sb2S3 achieves a power conversion efficiency of 6.4%, performing at almost 20% higher than devices based on a [hk0]‐oriented absorber. This work opens up new prospects for pursuing high‐performance Sb2S3 thin film solar cells by tailoring the crystal orientation. A planar heterojunction Sb2S3 solar cell with a n‐i‐p structure is fabricated through a hydrothermal method. By adding extrinsic Cd into the precursor solution, a Sb2S3 thin film with the preferred orientation of (hk1) is successfully deposited on top of CdS. Better carrier transport and suppressed charge recombination are realized due to the desired grain boundary alignment in the bulk and superior interfacial contact.