The prediction of the morphology and PCE of small molecular organic solar cells

Abstract

The efficiency of bulk heterojunction (BHJ) solar cells depends strongly on the morphology of the electron donors and electron acceptors in the active layer. Here we use Dissipative Particle Dynamics (DPD) simulation to predict the donor–acceptor morphology and graph theory to predict the efficiency of small molecular organic solar cells (SM OSCs). We focus on a recently reported small molecular organic solar cell based on a new molecule donor, DTS(PTTh₂)₂ and three molecules DR3TBDTT, DR3TBDTT-HD, and DR3TBD2T with a benzo[1,2-b:4,5-b′]dithiophene (BDT) unit. With our theoretical approach, we are able to study the critical factors affecting the morphology and efficiency such as, the chemical structure of the conjugated molecular, fullerene functional group, solvents, additives, blend ratio, and processing conditions (e.g., annealing temperature). Our results are consistent with experimental conclusions and provide useful guidelines for improving the efficiency of small organic solar cells.