Hansen Solubility parameters and Green Solvents for Organic Photovoltaics

The determination and prediction of solubility behavior of organic semiconductors to use them is very important.[1] The concept Hansen solubility parameters is applied for the study. HSPs for PC61BM were determined using HSPiP software. In this experiment, we used 20 and 39 solvents in the first and second phases of the experiment respectively to determine HSPs for PC61BM. The results obtained were 18.23, 3.75, and 4.51MPa1/2 for dispersive, polar and hydrogen bonding for the first and 17.58, 3.73 and 4.79 MPa1/2 for the second respectively. These results were compared to HSPs of chloroform, Limonene and Benzaldehyde. Limonene is used for cleaning in the electronic and printing industries, and in paint as a solvent. [2] It was selected as a solvent to replace the chlorinated type solvents. (HSPs) of Limonene, with δD, δP and δH of 17.20, 1.8 and 4.3 MPa1/2 respectively, were obtained from the HSPiP list of solvents and the calculated Relative Energy Difference of 0.333 for Limonene to PC61BM suggested that limonene could be a good non-chlorinated for solution processing of fullerene-based polymer solar cells. The Limonene processed active layer in this work displayed a maximum power conversion efficiency of 3.19 % and our results suggest that Limonene would be a promising solvent for environment – friendly fabrication of polymer solar cells if more efforts is done to improve the power conversion efficiency