D18-Cl, a chlorinated version of D18, is another highly efficient polymer semiconductor that is demonstrating over 18% PCE in non-fullerene polymer solar cells (NF-PSCs). When compared with D18, which has fluorinated thiophene side chains, D18-Cl shows deeper HOMO and LUMO energy levels.
A device efficiency of 18.12% and certified efficiency of 17.6% have been achieved using D18-Cl as the electron donor and N3 as an acceptor in a single junction non-fullerene polymer solar cell (NF-PSC) [1]. Further improvement of device performance to an outstanding PCE of 18.69% was obtained while a second acceptor PCBM was used in the active layer [2]. PCE of 20.8% was achieved by using D18-Cl as the polymer donor and BTP-4F-P2EH as the NFA acceptor by engaging the same layer-by-layer deposition method [3].