Zinc Chloride‐Treated Indium Sulfide as Buffer Layer for Cd‐Free Antimony Selenide Solar Cells

Abstract

In2S3, as a promising environmentally benign semiconductor, is used as a buffer layer in thin‐film solar cells due to its high electron mobility, low toxicity, and excellent thermal and chemical stability. The preparation of a high‐quality In2S3 film is crucial for the improvement of its carrier extraction ability and subsequent deposition of absorber layers. Herein, it is demonstrated for the first time that a posttreatment of In2S3 film with ZnCl2 solution is able to serve as buffer layer for constructing superstrate Sb2Se3 solar cells. The posttreatment with ZnCl2 not only prevents In2S3 from excessive oxidation during annealing process, but also facilitates the growth of (hk1) orientation of Sb2Se3, thereby improving the interfacial contact of In2S3/Sb2Se3. The improved heterojunction quality suppresses the carrier recombination at the interface, and enhances the charge extraction ability of In2S3. As a result, the power conversion efficiency of Sb2Se3 solar cell increases from 2.63% to 5.00%. Herein, a facile and effective strategy is provided for the application of In2S3 as the buffer layer in inorganic chalcogenide solar cells.

Advances on Sb2Se3 Solar Cells Fabricated by Physical Vapor Deposition Techniques

“…Spiro-OMeTAD as HTL has been employed in several works [68,72,77,82,94]. Z. Cao et al [94] recently investigated Spiro-OMeTAD as HTL and CdS as ETL.…”

“…The authors obtained a PCE of 3.44% for a Ag/ITO/ZTO/Sb2Se3/Mo/glass substrate solar cell, exploiting a Zn0.57Sn0.43O buffer layer.Y. Dong et al[82] investigated a ZnCl2-modified In2S3 ETL also for a Cd-free solar cell in a Au/Spiro-OMeTAD/Sb2Se3/In2S3/FTO solar cell. A ZnCl2 post-treatment favored a quality improvement of the In2S3 film, prepared by CBD, also inducing a longitudinal growth on the Sb2Se3 layer, fabricated via VTE.…”

A Review on the Fundamental Properties of Sb2Se3-Based Thin Film Solar Cells

“…TiO 2 [167], CeO 2 [172], ZnCdS [145], In 2 S 3 [173], CdSe [174] and CdS:O [175] are only some of the Sb 2 Se 3 partners studied to optimize energy band alignment through interface engineering. Moreover, to reduce interface defects, the surface of TiO 2 [176] and In 2 S 3 [177] films were treated with zinc halides. These attempts demonstrate that there is still much work to be completed to address the remaining knowledge gaps and to introduce successful strategies to minimize defect density in Sb 2 Se 3 films, both in the bulk and at the interface with HTM and ETM.…”

Tuning Surface Electronics State of P-Doped In2.77S4/In(OH)3 toward Efficient Photoelectrochemical Water Oxidation

“…Hydrogen production by solar energy through photoelectrochemical (PEC) systems are promising and practical strategies. − Typically, manipulation of the photogenerated carriers to inhibit their recombination is key to solar to hydrogen conversion. The two-dimensional (2D) numerical model calculation reveals a potential gradient existed on a highly constrained area near the surface of the semiconductor. , The spontaneous separation of photogenerated electron–hole pairs is inefficient, especially under a low external bias with a single semiconductor structure. Generally, specially designed heterostructures will result in a redistribution of free charges at the interface, Fermi level being flattened slightly, and a built-in electric field forming for spatial charge separation .…”

“…Recently, indium sulfide (In 2 S 3 )-based photoanodes have exhibited promising PEC water splitting activity . In 2 S 3 has a face-centered cubic crystal structure, suggesting excellent characteristics, including a narrowed band gap (2.0–2.8 eV) for harvesting visible light, highly carrier mobility (17.6 cm 2 V –1 s –1 ), and controllable electrical properties . Among which, n-type In 2.77 S 4 nanosheets possess the unique defect cubic phase spinel structure with plentiful vacancies, demonstrating a strong ability for charge transfer. , Additionally, 2D In 2.77 S 4 as a potential oxidation catalyst presents a short exciton diffusion distance, and the material’s thickness is less than the width of space charge region at solid/liquid interfaces. − Thus, In 2.77 S 4 was used for water splitting by the S -scheme, Z -scheme, and p–n heterojunction.…”