Fluorene-centered perylene monoimides as potential non-fullerene acceptor in organic solar cells

Abstract

A fluorene-centered perylene monoimide dimer, PMI-F-PMI with a partly non-coplanar configuration has been developed as a potential non-fullerene acceptor for organic solar cells (OSCs). The optimum power conversion efficiency (PCE) of the OSC based on PMI-F-PMI as acceptor and poly (3-hexyl thiophene) (P3HT) as donor is up to 2.30% after annealing at 150°C. The PCE of 2.30% is the highest value for the OSCs based on P3HT donor and non-fullerene acceptor lies in that PMI-F-PMI’s lowest unoccupied molecular orbital (LUMO) level around −3.50eV matches well with the donor P3HT to produce higher open-circuit voltage (Voc) of 0.98V. Meanwhile, PMI-F-PMI makes remarkable contribution to devices’ light absorption as the maximum EQE (30%) of the devices is at 512nm, same to the maximum absorption wavelength of PMI-F-PMI. The other favorable characteristics of PMI-F-PMI in bulk heterojunction (BHJ) active layers is proved through the photo current density measures, the relatively balanced electron–hole transport, and the smooth morphology with root mean square (RMS) value of 1.86nm. For these advantages, PMI-F-PMI overwhelms its sister PMI-F and parent PMI as an acceptor in BHJ solar cells.