Hybrid solar cells using a zinc oxide precursor and a conjugated polymer

We describe a new method towards bulk-heterojunction hybrid polymer solar cells based on composite films of zinc oxide (ZnO) and a conjugated polymer poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV). Spin-coating diethylzinc as a ZnO precursor and MDMO-PPV from a common solvent at 40 % humidity and annealing at 110 degrees C provides films in which crystalline ZnO is found to be intimately mixed with MDMO-PPV. Photoluminescence and photoinduced spectroscopy demonstrate that photoexcitation of these hybrid composite films results in a fast and long-lived charge transfer from the polymer as a donor to ZnO as ato be obtained n acceptor. Using the ZnO-precursor method, hybrid polymer solar cells have been made with an estimated air-mass of 1.5 (AM 1.5) energy conversion efficiency of 1.1 %. This new method represents a fivefold improved performance compared to similar hybrid polymer solar cells based on amorphous TiO2.