Spectroscopic and optoelectronic characterisation of solution-processed tin monosulfide solar cells

Abstract

Tin mono-sulphide (SnS) has emerged as a promising photovoltaic material because of the earth-abundance, non-toxicity and its optical properties. SnS exhibits a high absorption coefficient (>104cm-1) with an ideal band gap of 1.3 eV (ca. 950 nm), which make it an excellent light absorber for photovoltaic applications. To date, the highest power conversion efficiency (PCE) of SnS-based solar cells is up to 4.4% although the theoretical PCE is 32%; and SnS layers were obtained by atomic layer deposition and thermal evaporation. There are very few attempts using fast and cost-efficient methods; therefore, solution-processed fabrication methods for SnS thin films as well as the conjugated organic semiconductors to prepare hybrid solar cells are particularly interesting. This thesis explores the possibility of SnS as a new and promising light-harvesting absorber material. It focuses on the fabrication of a straight-forward, solution-based route for the preparation of SnS films, and optimisation of the surface coverage and the morphology which are monitored by a range of characterisation techniques. In particular, an exhaustive transient absorption spectroscopy (TAS) study has elucidated the key parameters that influence the optoelectronic properties of SnS/organic hybrid systems. Furthermore, a systematic study of the effects of processing parameters on the device efficiency was carried out which reveals the optimal conditions for efficient SnS-based solar cell performance.Open Acces