Efficiency Improvement of Organic Solar Cells by Slow Growth and Changing Spin-Coating Parameters for Active Layers

• Published in: Japanese Journal of Applied Physics Vol. 50; no. 2; pp. 022301 - 022301-4
• Main Authors: Tsai, Yu-Sheng, Chu, Wei-Ping, Juang, Fuh-Shyung, Tang, Rong-Ming, Chang, Ming-Hua, Hsieh, Tsung-Eong, Liu, Mark O
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.02.2011
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.50.022301

The derivatives of C 60 , [6,6]-phenyl C 61 -butyric acid methyl ester (PCBM), and 3-hexylthiophene (P3HT) were dissolved in o -dichlorobenzene (DCB) solvent, and then spin-coated as an active layer for polymer solar cells. The experimental parameters including the spin-coating speed and drying conditions for the active layer, were studied carefully to obtain the optimum power conversion efficiency (PCE). In the active layer drying procedure, the DCB solvent saturated/unsaturated vapor pressure was adjusted by controlling the amount of solvent at a half-open capacity. The DCB solution was used to enhance the self-organization of the active layer of P3HT and to reduce the number of pure PCBM clusters. In the DCB optimum solution, the PCE of a polymer solar cell can be increased from 1.36 to 1.79%. The structure corresponds to a nano-to-micron scale ordering in the unsaturation-treatment films. In the optimum unsaturation procedure, the PCE of a polymer solar cell can be increased from 1.79 to 2.53%. Using two steps with optimum rotation speeds in the active layer spin-coating, the surface uniformity can be improved, with the PCE increased from 2.53 to 3.13%.