Studies On Photovoltaic Performance Of Double-Cable Single Component Organic Solar Cells

Bulk heterojunction(BHJ)organic solar cells(OSCs),containing a mixture of an electron donor and an electron acceptor materials,have attracted extensive attention in both research and industry field during the past decades due to their advantages of simple preparation process,low cost,flexible folding,etc..Due to the rapid developing of non-fullerene electron acceptors during the past several years,power conversion efficiency(PCE)of organic solar cells based on BHJ system has been over 16%.Unfortunately,the electron donor(D)or acceptor(A)materials are easy to aggregate under long time illumination during the device working.Then,large D/A phase separations are induced,which would reduce the excitons separation efficiency and decrease the device performance and stability.In a single-component OSC,the active layer is spin-coated from solution of single conjugated copolymer with donor and acceptor segments binding with covalent.Thus,excessive aggregation of the donor/acceptor materials are inexistence.The single component OSC provides an effective method to simplify the device fabrication process and improve device stability.However,the PCE of single-component OSCs is much lower than thoes of BHJ OSCs.The main reason is that in the single-component active layer,the phase separation between the donor and acceptor segments is small and difficult to control.This makes the free charge carriers recombination efficiency increases.So,PCE of the device is limited.Therefore,tuning the phase separation between the donor and acceptor segments is the key to improve the photovoltaic performance of single-component OSCs.In this work,PBDB-T and NDI,PBDB-T-Cl and PBI are used as electron donor and electron acceptor materials in BHJ active layers,respectively,to compare their single-component solar cells,and proposed a method to improve the photovoltaic performance of single-component organic solar cell devices.