Ternary donor-insulator-acceptor systems for polymer solar cells

A series of block copolymers with fixed length of the semiconductor-block poly(3-butylthiophene) (P3BT) and varying length of the insulator-block polystyrene (PS) are synthesized. These copolymers are blended with phenyl-C61-butyric acid methyl ester (PCBM) for the bulk heterojunction photoactive layers. With appropriate insulator-block length and donor-acceptor ratio, the power conversion efficiency increases by one order of magnitude compared with reference devices with pure P3BT/PCBM. PS blocks improve the miscibility of the active layer blends remarkably. The P3BT-b-PS crystallizes as nanorods with the P3BT core covered with the PS-block, which creates a nanoscale tunneling barrier between donor and acceptor leading to more efficient transportation of charge carriers in the semiconductors. Copolymers containing poly(3-butylthiophene) (P3BT) and polystyrene (PS) blocks are synthesized and used as donor materials for polymer solar cells (PSCs). One order of magnitude performance improvements are made by such insulator involved PSCs compared with corresponding device of pure P3BT. Appropriate PS block are demonstrated to increases the miscibility of the donor-acceptor blends and charge transportation in the conductive domain.