Single and double layer bulk heterojunction organic solar cell.

Abstract

Bulk heterojunction photovoltaic device based on the binary organic comprised of P3HT:PCBM and PTB7:PCBM with weight ratio of 1:1 and 1:1.5 respectively. We used these blends as a photo-active layer with different structures such as single layer of the P3HT:PCBM and PTB7:PCBM, as well as top-down and bottom-up as double layers of the two active layers respectively. These layers were deposited using two different simple and inexpensive techniques such as spin-coating and roll-to-roll (R2R) under ambient laboratory conditions. The current density-voltage (J-V) characteristics, optical and morphological properties were investigated. The J-V characteristics exhibited average of power conversion efficiency of 2.7% for single binary layer blend and 1.3% of double layer blend. The optical absorption band of a double layer binary blends was extended better than single layer. However, the device performance of the double layer was found too low due to poor charge transport processes in the medium. This is an encouraging development toward achieving low cost organic photovoltaic devices based on single layer ternary blend active layer.