Design,Development Of Acceptors For All-Polymer Solar Cells

All polymer solar cells(all-PSCs),consisting of both conjugated polymers as electronic donor and acceptor,are considered as a class of potential organic solar cells due to their possess unique advantages,including of phase stability,mechanical strength and good stability.Recently,remarkable progress has been made in the development of high-mobility acceptor,optimization of molecular packing orientation as well as blend morphologies over the past several years,however the device performance of all-PSCs is still inferior to that of PSCs with fullerene and small molecular non-fullerene acceptors.Here,a series of novel polymer acceptors around the perylene diimide(PDI)and naphthalene diimide(NDI)units were developed and successfully applied to all-polymer solar cell devices.In chapter 2,we present a series of isomeric PDI-based conjugated polymers(PA and MA)with parallel and non-parallel PDI units inside backbones as efficient electron acceptors in all-PSCs.Although having similar dihedral angles in space,PA and MA exhibit different physicochemical properties,such as solubility,due to their different configurations in space.It was found that paralinked conjugated polymers(PA)showed better solubility,stronger ?-? stacking,more favorable blend morphology,and higher photovoltaic performance.Device based on PA showed significantly enhanced photovoltaic performance than that of MA.In addition,we also synthesized a series of terpolymeric acceptors,in which the performance of the device based on PA-M01 was 4.11%.In chapter 3,we successfully synthesized two novel polymer acceptors PPDI-TO and PNDI-TO by introducing strong electron donating unit-alkoxythiophene into the main chains of the conjugated polymers.The introduction of alkoxythiophene can effectively raise the LUMO energy levels of the polymers and broaden the absorption spectra of the polymers.PCEs of 2.8% and 3.7% can be achieved for devices based on PPDI-TO and PNDI-TO,respectively.In chapter 4,we introduce a less sterically hindered bisfuran instead of the thiophene in N2200 to synthesize a new N-type polymer NFu.The DFT shows that the NFu molecular plane has a smaller dihedral angle than N2200,so the NFu molecules have stronger ?-? stacking.Spectral absorption also showed that the absorption of NFu in the long-wave region was significantly enhanced.PCE of the device based on PTzBI and NFu is 7.80%,indicating that NFu is a potential high-efficiency organic solar cell acceptor material.