Study of charge transfer in D-A conjugated donor and non-fullerene small molecule acceptor for the application of non-fullerene polymer organic solar cell

Abstract

The progress in Bulk Heterojunction-Polymer Solar Cells (BHJ-PSCs) has received much interest since the emergence of non-fullerene small molecule acceptors (NFSMAs), and power conversion efficiency (PCE) have reached up to 18%. In general, a mixer of conjugated polymer Donor and NFSM as Acceptor consists of the BHJ photoactive layer. Their optical bands and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are of great importance to improve the resulting PSCs' efficiency and performance of the polymer solar cells. The HOMO and LUMO of Poly(4,6-bis(5-octylthiophen-2-yl)benzo[1,2-b:6,5-b':3,4-c'']terthiophene-2,8-diyl)-alt-(thiophen-2,5-diyl]-alt-(5,6-difluoro benzo[c][1,2,5]thiadiazol 4,7-diyl (denoted as P95) and NFSMAs ITIC-F, were measured using cyclic voltammetry(CV). Optical bandgap energy for each material's were calculated by UV–VIS absorbance spectra. Further charge transfer study was carried out by photoluminescence (PL) spectroscopy. It's results show that efficient electron transfer from P95 to ITIC-F and hole from ITIC-F to P95. On the basis of experimental outcomes these polymer materials can effectively produce viable organic solar cell (OSCs) devices.