Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia; School of Chemisty and Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottsville 3209, South Africa
Abera, N., Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia; Tessema, G., School of Chemisty and Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottsville 3209, South Africa
The compositional dependence of the performance of the blends of [3-(4-octylphenol)-2,2′-bithiophene] (PTOPT) and 6,6-phenyl-C61-butric acid methyl ester (PCBM) sandwiched between ITO/PEDOT:PSS and Al was studied. The observed dark current-voltage curves showed that the current (J) is space charge limited except at low voltages (V). The best power conversion efficiency (η) and short circuit current (JSC) were found at 72% PCBM loading. Moreover, we have observed significant reduction on the fill factor with increasing PCBM concentration due to high recombination of charge carriers. The impedances across the electrodes were discussed based on low frequency impedance analyzer measurements. © 2013 Published by NRC Research Press.