Study On The Polymer Solar Cell Photovoltaic Performance Property Of Quinoxaline Polymer Electron Donor Materials Based On Thioether Side Chains

Polymer solar cells have attracted more and more attention due to the advantages of flexibility,light weight and the capability of mass production.With the help of materials synthesis and device engineering,the power conversion efficiency of PSCs has been continuously promoted.In this paper,based on our newly synthesized quinoxaline polymer donor material,binary and ternary polymer solar cells were prepared by combining with different acceptor materials.The influence of the type of acceptor materials and device engineering process on the device performance was systematically studied.The main work of the paper is as follows:(1)Polymer donor PBDT-DFQX1 that contains a linear alkylthio as side chain group was synthesized,and combined with PC70BM,ITIC and ITTC acceptor materials to prepare three typical polymer solar cells.Influence of the type of acceptor materials and device engineering process on the device performance was systematically studied.The results show that the power conversion efficiency of the devices based on PC70BM,ITIC and ITTC were 6.19%,6.42%and 9.70%,respectively,which proves that good spectral complementarity between donor material and acceptor material is a necessary condition for achieving high performance polymer solar cells.Innovatively applying SBS as an additive in fabricating ITIC based device,it was found that more orderly molecules arrangement in the active layer were formed with the help of SBS,and the phase separation behavior between donor and acceptor can be adjustable.Under the synergistic effect of the improved fill factor and short circuit current values,the power conversion efficiency of the ITIC based device was improved from 6.42%to 7.46%.(2)O-IDTBR and N2200 acceptor materials that have a smaller difference in the HOMO/LUMO energy level with polymer donor PBDT-DFQX1 were selected to fabricate non-fullerene polymer solar cell(PBDT-DFQX1:O-IDTBR)and all-polymer solar cell(PBDT-DFQX1:N2200).It was found that with thermal annealing treatment,an enhancement in absorption and more regular molecular arrangement were observed in active layers.A small HOMO/LUMO energy levels difference between donor and acceptor does not affect the exciton separation and charge transport behavior,but helps to reduce the voltage loss values,thereby improving the photovoltaic performance of the device.Finally,a low voltage loss of 0.56V along with a power conversion of 8.67%and 6.66%were obtained in PBDT-DFQX1:O-IDTBR and PBDT-DFQX1:N2200 system,respectively.(3)Ternary all polymer solar cell was fabricated using J52 and PBDT-DFQX1 with complementary spectra as donor and N2200 as acceptor,and a power conversion efficiency of 7.99%was obtained.It was found that the working mechanism of this kind of the ternary all polymer solar cell belong to parallel-like working mechanism.Energy transfer from J52 to PBDT-DFQX1 was observed.High-resolution AFM test results revealed that the addition of the third component make the phase diagram of the active layer change from a bicontinuous structure of the binary cells to the island structure of the ternary cells.