The Molecular Design Of Backbones And Side Chains For Two Typical Polymer Photovoltaic Materials And Device Optimization For Solar Cells

The molecular design of polymer photovoltaic(PV)materials and device optimization are the main means to improve the power conversion efficiency(PCE)of polymer solar cells(PSCs).Through the molecular design of backbones and side chains,the absorption spectra,extinction coefficients,molecular energy levels,and hole mobilities of the polymers can be effectively adjusted.In this paper,two kinds of typical PV polymers were selected,and the performance of the PSCs based on these polymers were improved though the molecular design of backbones and side chains of the polymers and the device optimization of the PSCs.The main results are as follows:1.Four PV polymer based on DTG unit were synthesized by the backbone design,and the photoelectric properties,crystallinity and their application in PSCs were systematically studied.The results indicated that the PV properties of these polymers can be effectively improved by the backbone design.2.Polymer PB1-S was designed and synthesized by introducing alkylthio groups on the side chains of the polymer PB1.Compared to PB1,the polymer PB1-S exhibihted higher molar extinction coefficient and hole mobility,resulting in substantial increasing of short-circuit current density(Jsc)and PCE of the PSCs.3.A series of polymers based on BDT units were synthesized by the structure design of backbone and side chains,the basic properties of these polymers and their application in non-fullerene PSCs were systematically studied and a high PCE of 10.49%was recorded.4.The interface optimization of high efficiency non-fullerene PSCs based on PB1:IT-M was studied.By comparing the different performances of the cathode interface PFN and PFN-Br in the devices,the electron transport mechanism at the cathode interface was proposed,which provided the information for the selection of the cathode interface in non-fullerene PSCs.