مشخصات پژوهش

Poly(3-thiophene ethanol) (P3ThEt)-graft-polystyrene (PSt) bottlebrushes were synthesized and applied in active layers of poly (3-hexylthiophene) (P3HT):phenyl-C71-butyric acid methyl ester (PC71BM) solar cells as morphology compatibilizers. In the presence of 15 wt% of P3ThEt-graft-PSt bottlebrush compatibilizers, the P3HT crystallite dimensions (D(100) = 45.67 nm and D(020) = 30.12 nm) and Rmean (38.96 nm) of PCBM clusters were the largest and the layer spacings were all the smallest (d(100) = 1.054 nm, d(020) = 0.301 nm and d(PCBM) = 0.406 nm). These dimensional properties led to better hole (1.9 × 10−3 cm2 V−1 s−1) and electron (1.2 × 10−2 cm2 V−1 s−1) mobilities. The content of bottlebrushes was optimized at 15 wt%, and thereby the best photovoltaic results including the maximum cell efficiency of 5.37% were obtained for this turning point (12.75 mA cm−2, 61%, 0.69 V). On exceeding the optimum weight percentage, all photovoltaic parameters decreased markedly and reached even less than that of pristine devices (1.92% versus 2.24%). After an optimum weight percentage of compatibilizers, further enhancement in bottlebrush content in active layers saturated and finally oversaturated the system and, consequently, the cell parameters significantly decreased. Accumulation of bottlebrushes in interfaces and donor/acceptor phases ruined the system function even with large and packed P3HT crystallites and PC71BM clusters.