Annealing induced control of trap-assisted recombination in vacuum-deposited small-molecule solar cells

• Role of thermal annealing on the co-evaporated SMOSC is elucidated in detail. • AFM morphology studies reveal improved crystallinity of D/A blend film. • PCE improvement of ≈195% upon annealing the active layer is observed. • Annealing leads to reduced trap-assisted recombination and hence better J SC . Vacuum-deposited small-molecule organic solar cells based on DTDCTB (donor) and C 70 (acceptor) molecules were systematically investigated for their solar-cell parameters and also the influence of thermal annealing on the morphology of the active layer. A detailed analysis is presented herewith, to understand the impact of thermal annealing on active layer nano-morphology and the origin of improved device performances via control over the trap-assisted charge recombination that directly affects the short-circuit current.