Recent Progress and Challenges in Controlling Secondary Phases in Kesterite CZT(S/Se) Thin Films: A Critical Review

Abstract

Kesterite-based copper zinc tin sulfide (CZTS) and copper zinc tin selenide (CZTSe) thin films have attracted considerable attention as promising materials for sustainable and cost-effective thin-film solar cells. However, the successful integration of these materials into photovoltaic devices is hindered by the coexistence of secondary phases, which can significantly affect device performance and stability. This review article provides a comprehensive overview of recent progress and challenges in controlling secondary phases in kesterite CZTS and CZTSe thin films. Drawing from relevant studies, we discuss state-of-the-art strategies and techniques employed to mitigate the formation of secondary phases. These include a range of deposition methods, such as electrodeposition, sol-gel, spray pyrolysis, evaporation, pulsed laser deposition, and sputtering, each presenting distinct benefits in enhancing phase purity. This study highlights the importance of employing various characterization techniques, such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, for the precise identification of secondary phases in CZTS and CZTSe thin films. Furthermore, the review discusses innovative strategies and techniques aimed at mitigating the occurrence of secondary phases, including process optimization, compositional tuning, and post-deposition treatments. These approaches offer promising avenues for enhancing the purity and performance of kesterite-based thin-film solar cells. Challenges and open questions in this field are addressed, and potential future research directions are proposed. By comprehensively analyzing recent advancements, this review contributes to a deeper understanding of secondary phase-related issues in kesterite CZT(S/Se) thin films, paving the way for enhanced performance and commercial viability of thin-film solar cell technologies.

Environmentally Friendly Pathway to Kesterite Nanoparticles with Controlled Sn Content: An In-Depth Study of Magnetic and Optical Properties

“…Over the last few decades, significant advancements have been made in the performances of thin-film solar cells based on CIGS (copper indium gallium selenide), CIS (copper indium sulfide), and CdTe technology. − However, their reliance on expensive, toxic, and scarcely available elements like cadmium, tellurium, and indium poses environmental and economic challenges . In this context, kesterite Cu 2 ZnSnS 4 (CZTS) emerges as a highly promising inorganic semiconducting compound for the production of low-cost thin-film photovoltaic devices because it is composed of easily available, cheap, nonpoisonous, and earth-abundant elements. − Current performances of CZTS solar cells are well below the Shockley–Queisser limit, and this is usually ascribed to the presence of defects and secondary phases, which heavily reduce the open-circuit voltage of the device . In particular, lattice defects induce the so-called “band tailing”, − reducing the charge-carrier generation rate and favoring nonradiative recombination processes. , Even if the efficiencies of CZTS-based solar cells are lower compared to other technologies from the same family, the use of environmentally friendly materials allows targeting specific applications such as building-integrated photovoltaic, flexible, and agrivoltaic solar cells. , Moreover, characterization through advanced techniques can provide a deep understanding of defects in kesterites, unlocking their full potential and the development of efficient and affordable thin-film photovoltaic devices.…”