title: Understanding the phase formation kinetics of nano-crystalline kesterite deposited on mesoscopic scaffolds via in situ multi-wavelength Raman-monitored annealing.
abstract: Kesterite, a highly promising photo-absorbing crystalline form of Cu2ZnSnS4(CZTS), has been prepared via various routes. However, the lack of in-depth understanding of the dynamic phase formation process of kesterite leads to difficulties in optimizing its annealing conditions, hence its light harvesting performance. In this paper, in situ Raman monitored-annealing is applied to study the phase formation kinetics of nano-crystalline kesterite from a precursor deposited on a TiO2mesoscopic scaffold. By performing in situ Raman annealing under different experimental conditions and wavelengths, several facts have been discovered: kesterite crystallization starts at as low as 170 °C, but after short time annealing at 300 °C followed by cooling, the initially formed kesterite is found to decompose. Annealing at 400 °C or higher is proven to be sufficient for stabilizing the kesterite phase. Annealing at the higher temperature of 500 °C is necessary though to promote a complete reaction and thus eliminate the parasitic copper tin sulfide (CTS) impurity intermediates identified at lower annealing temperatures. More importantly, the real-time temperature dependence of Raman peak intensity enhancement, shift and broadening for CZTS is established experimentally at 500 °C for 1 h, providing a valuable reference in future CZTS research. This work demonstrates the significance of using in situ Raman spectroscopy in elucidating the kesterite phase formation kinetics, a critical step towards full crystal phase control - a prerequisite for developing fully functional CZTS-based optoelectronic devices.
authors.affiliation: Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada. george.demopoulos@mcgill.ca.
authors.forename: Zhuoran
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Département de chimie, Université de Montréal, 5155, Avenue Decelles, Montreal, QC H3T 2B1, Canada.
authors.forename: Samir
authors.initials: S
authors.lastname: Elouatik
authors.affiliation: Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada. george.demopoulos@mcgill.ca.
authors.forename: George P
authors.initials: GP
authors.lastname: Demopoulos