P3HT based solution-processed pseudo bi-layer organic solar cell with enhanced performance

We present a solution-processed pseudo bi-layer organic solar cell with poly(3-hexyl thiophene) (P3HT) as donor and indene-C60 bisadduct (ICBA) as acceptor. The devices were fabricated by sequential processing of the active components followed by a thermal annealing treatment. An efficiency of 5.9% was achieved under AM 1.5G irradiation (1000 W/m2). The obtained efficiency is attributed to an enhanced nanomorphology that arises from the inter-diffusion of the ICBA molecules into a layer of pre-organised polymer (P3HT) and also due to the subsequent crystallisation of the ICBA molecules. These processes facilitate efficient charge generation and extraction. Time of flight-secondary ion mass spectroscopy (TOF-SIMS) depth profiling was carried out for different thermal annealing treatments of these pseudo bi-layer devices, which reveals full inter-diffusion of ICBA into the polymer P3HT. Photo-CELIV (charge extraction by linearly increasing voltage) studies elucidates that the thermal annealing imparts crystallinity to the fullerene phase which results in the improvement of charge carrier mobility.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Solution-processed pseudo bi-layer organic solar cell. ► Sequential processing of the active components followed by a thermal annealing treatment. ► Inter-diffusion of the ICBA molecules into a layer of pre-organised polymer, P3HT. ► Thermal annealing imparts crystallinity to the fullerene phase which results in the improvement of charge carrier mobility. ► Pseudo bi-layer organic solar cell exhibits an efficiency of 5.9%.