RESUMEN
The one-dimensional photovoltaic absorber material Sb2S3 requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted the vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3 on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface, which creates a beneficial bonding environment between exposed Cd2+ dangling bonds and S atoms in the Sb2S3 molecules. The CdS/VTD-Sb2S3 interface recombination is suppressed by such properly aligned ribbons at the interface. Compared to typical [120]-oriented Sb2S3 films deposited on CdS by the rapid thermal evaporation (RTE) method, the VTD-Sb2S3 thin film is highly [211]- and [121]-oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of indium tin oxide (ITO)/CdS/Sb2S3/Au. This work provides a potential way to obtain vertically aligned thin films on different buffer layers.
RESUMEN
We report a highly effective surface treatment method for planar-type Sb2S3 solar cells by employing a Cs2CO3-modified compact TiO2 (c-TiO2) electron transport layer. It is found that surface treatment using a Cs2CO3 solution can shift the work function of c-TiO2 upward and reduce its surface roughness. As a result, compared with the power conversion efficiency of untreated solar cells, that of the treated solar cells with a glass/FTO/c-TiO2(/Cs2CO3)/Sb2S3/P3HT/Au structure significantly improved from 2.83 to 3.97%. This study demonstrates that the introduction of Cs2CO3 on a c-TiO2 layer is a simple and efficient way to adjust the work function of the electron transport layer and fabricate high-performance planar-type Sb2S3 solar cells.
RESUMEN
Poor thermostability of Sb2S3 in vacuum hinders the possibility of achieving high-quality crystalline films. In order to enhance the photovoltaic properties of Sb2S3 planar heterojunction solar cells, a selenylation-based post-treatment approach has been employed. Selenylation performed over 15 min on the Sb2S3 film resulted in an enhancement in the conversion efficiency from ~ 0.01 to 2.20%. Effect of the selenylation on the evolution of morphology, crystal structure, composition distributions, and photovoltaic behavior has been investigated. The variation in the energy levels of Sb2S3/CdS junction has been also been discussed. Results show that selenylation not only enhanced the crystallinity of Sb2S3 film but also provided a suitable energy level which facilitated charge transport from absorber to the buffer layer.