In this work, we used solvent mixtures, consisting of 1-chloronaphthalene (Cl-naph), one solvent with a high boiling point, and o-dichlorobenzene, to prepare the polymer films for polymer photovoltaic devices. Because of the lower vapor pressure of the solvent mixtures, the polymer films dried slower. With higher Cl-naph concentration in the organic solvent, the polymer chains had longer time to self-organize themselves. As a result, the higher degree of crystalline led to lower device series resistance, thereby increasing the performance of the photovoltaic devices.

The influence of anode buffer layers on the performance of polymer photovoltaic devices based on blends of poly͑3-hexylthiophene͒ and ͓6,6͔-phenyl-C-61-buytyric acid methyl ester has been investigated. The buffer layers consist of poly͑3,4-ethylenedioxythiophene͒:poly͑styrenesulfonate͒ ͑PEDOT-PSS͒ doped with different concentrations of mannitol. Improved power conversion efficiency, up to 5.2%, has been observed by reducing the resistance of PEDOT:PSS after doping. One extrapolation method has been developed to exclude the resistance from the connection of the electrodes from the total device resistance. The results confirm that the device improvement is due to the reduction of series resistance of the PEDOT:PSS after the mannitol doping.

No abstract