Inverted low-bandgap polymer solar cells with long-term stability

Stable polymer solar cells based on an intrinsically air-stable conducting polymer, a-PTPTBT, in inverted structure are investigated. After surface modification of ITO for the subsequent film deposition, the device shows a improvement of power conversion efficiency from 2.45% to 3.31%, and exhibits very high stability. The device retains over 95% of its maximum efficiency even after 1,500 hours storage in ambient conditions. All the layers between the electrodes in the device were processed with solution, which could greatly reduce the production cost and simplifies the fabrication process. This strategy provides a possible route to achieve commercially applicable organic solar cells.