Crown-ether functionalized fullerene as a solution-processable cathode buffer layer for high performance perovskite and polymer solar cells

Abstract

An alcohol-soluble fullerene derivative functionalized with a crown-ether end group in its side chain (denoted as PCBC) was synthesized and applied as a cathode buffer layer in planar p–i–n perovskite solar cells and bulk-heterojunction polymer solar cells. It is found that the introduction of the PCBC cathode buffer layer can greatly improve the photovoltaic performance of the planar p–i–n perovskite solar cells based on CH₃NH₃PbI_3−xCl_x with power conversion efficiency (PCE) reaching 15.08%. In addition, the bulk-heterojunction polymer solar cells based on PBDTTT-C-T:PC₇₀BM with the PCBC cathode buffer layer also showed a higher PCE of 7.67%, which is improved in comparison with the traditional device with the Ca/Al cathode. This work indicates that PCBC is a promising solution-processable cathode buffer layer material for application in both planar p–i–n perovskite solar cells and bulk-heterojunction polymer solar cells.