Organic Thin Film Solar Cell Composed of Hetero-Deposited Langmuir-Blodgett Films

Organic thin film solar cells composed of the hetero-deposited Langmuir-Blodgett (LB) films were fabricated using poly(3-hexylthiophene) (P3HT) as a donor, [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an acceptor and poly(N-dodecylacrylamide) (pDDA) as an amphiphilic polymer. Various types of the solar cell such as the bulk heterojunction (BHJ) type, p-n heterojunction type, double layer BHJ type and P3HT single layer type solar cells were constructed and their photovoltaic properties were compared with them. The short circuit current densities observed at all the solar cells fabricated by LB technique were three orders of magnitude smaller than that of BHJ solar cell fabricated by spin-coating method because of the film resistance of the existence of pDDA for forming LB film. The open circuit voltage is interestingly obtained to be 1.23, 0.82 and 1.06 V at the P3HT single layer type, p-n heterojunction type and the double layer BHJ type solar cells fabricated by LB technique, resulting to be higher than 0.52 V at the BHJ type solar cell. The phenomena demonstrate that the hole produced by photoinduced charge separation can be accumulated at the P3HT layer of the solar cells.