Novel Siloles And Lactam Acceptor Units For Organic Solar Cells

Organic solar cells(OSCs)have attracted great interest due to their light-weight,low cost and flexibility.Polymer solar cells(PSCs)are mainstreams in the field.So far,exploitation of the active layers of PSCs is mainly concentrated on PCBM or non-fullerene small-molecule acceptors and donor-acceptor(D-A)polymers for donors.Non-fullerene n-type small-molecule acceptors,compared with PCBM,possess low cost,adjustable energy levels and good solubility.What’ s more,small-molecule acceptors show wider spectral absorption that benefit light harvest for higher short-circuit current density.Therefore,it is necessary to develop new non-fullerene small-molecule acceptor materials boosting to high-performance OSCs.For donor materials,D-A conjugated polymers with large planar fused-ring structure donor or acceptor units benefit for the extensition of their absorption,and the improvement of the mobility of electrons and holes,which enhance the power conversion efficiency of solar cells.But much attention has been paid to fused-ring donor units rather than acceptor units.In this paper,we designed and synthesized some new OSCs materials.Firstly,we designed and synthesized some silole small-molecule acceptors.Secondly we designed and synthesized some novel fused-ring lactam acceptor units.Then we investigated their optical,electrochemical,photovoltaic and other properties.The main contents and results are summarized as follows:1.We developed a kind of silole small-molecule acceptors 2,2’-((2Z,2’Z)-((4,4,4’,4’-tetrahexyl-4H,4’H-[2,2’-bisilolo[3,2-b:4,5-b’]dithiophe ne]-6,6’-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diyli dene))dimalononitrile(STIC6),and prepared PTB7-Th:STIC6 solar cells.But the solubility of the mixed PTB7-Th:STIC6 solvent was poor,so 2,2’-((2Z,2’Z)-(4,4,4’,4’-tetraoctyl-4H,4’H-[2,2’-bisilolo[3,2-b:4,5-b’]dithiophe ne]-6,6’-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diyli dene))dimalononitrile(STIC8)was synthesized.The PCE of PTB7-Th:STIC8 solar cells was higher than that of PTB7-Th:STIC6 solar cells.2.We developed an innovative fused-ring lactam acceptor unit[2,2’-bidithieno[3,2-b:2’,3’-d]pyridine]-5,5(4H,4’H)-dione(BDTPi).Two copolymers,PThBDTPi and PSeBDTPi,were synthesized by using thiophene and selenium as the donor unit respectively,and BDTPi as the acceptor unit.Both of them have good thermal stability and light absorption.The optical band gap of PThBDTPi is 1.88ev,and PThBDTPi:PC71BM solar cells afford an outstanding PCE up to 8.11%.3.We studied the effect of isomeric structures of acceptor units on photovoltaic performance of polymer solar cells.The conclusion can be got that more attention should be paid to isomeric structures when we develop an innovative polymer.