Sb2S3 as sensitizer in semiconductor-sensitized solar cells

Abstract

Dye-sensitized solar cell (DSSC) is an emerging technology with the potential to surpass first generation silicon-based solar cells and second generation thin film solar cells. To date, DSSCs have already reached efficiency of over 11 % but it has yet to display widespread commercial application in the solar panel market. This is largely due to its degradation and stability of the cell as well as the use of a liquid electrolyte which can result in leakage. Hence, this study aims to explore new materials to replace the dye and electrolyte. Antimony sulfide (Sb2S3) has been identified as a suitable candidate.

In this project, Sb2S3 has been successfully incorporated into semiconductor-sensitized solar cells (SSSCs). Sb2S3films were deposited via chemical bath deposition (CBD) at various deposition times and temperatures. Photoanode, control of recombination and hole transport materials were studied to investigate and enhance photovoltaic performance in SSSCs. Studies on TiO2 nanoparticles size and thickness allowed a better understanding of the growth mechanism of CBD. Although smaller nanoparticle size provides a much larger effective surface area for sensitizer attachment, the smaller pore size leads to an over-aggregation of Sb2S3 particles on the surface pores. An optimum nanoparticle size of >100nm was established and reported to exhibit light scattering effect, achieving an efficiency of 2.2 %. Furthermore, In(OH)xSy was explored as a recombination barrier and found to enhance photovoltaic performance despite its insulating nature. Two different hole transporting materials, spiro-OMeTAD and P3HT, were also compared to study their differences, arising from hole mobility and fabrication ease. Lastly, a novel post treatment, comprising of thermal oxidation and acid etching, was successfully adopted and showed mark improvement in the device performance.

Sb2S3 has proved to be a promising sensitizer largely due to its relatively high absorbance, contributing to good photovoltaic performance, as well as ease and cost of fabrication, via the conceptually simple chemical bath deposition.