An insight into the mechanism of charge transfer of organic (P3HT): inorganic (CZTS) composites for hybrid photovoltaics

In the present work, Cu2ZnSnS4 (CZTS) nanoparticles were prepared with different S-sources using a hot injection colloidal route. The morphological and structural properties have been analyzed. The dendrimers like nanocrystals were observed using thiourea while, spherical and triangular-shaped nano-particles were observed using elemental-S, and 1-Dodecanthiol (1-DDT) respectively. The charge transfer studies have been carried out and analyzed using Stern-Volmer curves for all three CZTS NPs with P3HT solution. CZTS NPs with thiourea as S-source were found to have the best charge-transfer capabilities. These nanoparticles were then mixed with a polymer and aromatic fullerene and were used as the active layer material for the hybrid photovoltaic solar cell. The increment of 34% power conversion efficiency (PCE) was observed with a small amount (6%) of CZTS nanoparticles. Surface morphology observed using atomic force microscopy of an active layer shows an increase in PCE with the decrease in the roughness of the film.