Synthesis For Properties Of Cross-linked Polymer Donor Materials Based On PM6

Recently,various high-efficiency polymer donor materials have been developed in which power conversion efficiencies（PCEs）have exceeds 19%in single-junction organic solar cells（OSCs）.This paper summarizes the development history of OSCs,for polymer donor materials with benzo[1,2-b:4,5-b’]dithiophene（BDT）as the electron-rich（D）unit.Aiming at the unstable morphology of OSCs,a cross-linking polymer strategy was proposed for 1,6-bis（2,5-dibromothiophen-3-yl）hexane（TC6T）,1,8-Bis（2,5-dibromothiophen-3-yl）octane（TC8T）for 2,5-bis（（Z）-2-（2,5-dibromo thiophen-3-methyl）ethenyl）thiophene（TVTVT）cross-linking units were developed.The influence of cross-linking unit on the absorption spectrum,energy level,charge mobility for the morphology of OSCs were studied.The main results are as follows:（1）The cross-linking unit TC6T for two cross-linking polymer donor materials PM6-TC6T-3 for PM6-TC6T-5 were synthesized.by systematically studying the photophysical properties,electrochemical properties,active layer morphology for photovoltaic properties of PM6-TC6T-3 for PM6-TC6T-5,it is revealed that the cross-linking unit can affect the morphology for charge transfer of OSCs.A unique internal network structure can be formed to enhance the charge transport,for adjust the FF,thereby improving the photovoltaic performance of OSCs.The PM6-TC6T-3:Y6-based device achieved a PCE of 16.83%for the PM6-TC6T-5:Y6-based device achieved a PCE of 14.37%.（2）by control the length of the alkyl chain,thecross-linking unit TC8T was synthesized.It is proposed to change the length of the alkyl chain,adjust theπ-πstacking distance between donor material for active layer morphology of OSCs.The PM6-TC8T-3 for PM6-TC8T-5 have a more obvious internal network structure for more balanced charge transport,resulting in higher FF for J_sc.The PM6-TC8T-3-based device achieved a PCE of 16.04%for the PM6-TC8T-5-based device achieved a PCE of 16.18%.（3）A conjugated cross-linked unit TVTVT was synthesized for the effect of cross-linked unit on the carrier mobility for the morphology of OSCs was discussed.The inner network structure is more dense for the charge transport is worse.The PM6-TVTVT-3-based device achieved a PCE of 14.29%for the PM6-TVTVT-5-based device achieved a PCE of 14.12%.