Synthesis Of Small Molecules Based On IDT Derivatives And Application In Organic Solar Cells

After the unremitting efforts of scientists,solar cells have made an impressive development.Organic solar cells have received extensive attention owing to the advantages of with low cost,light weight,facile large area preparation.Therefore,this thesis is focused mainly on the design and synthesis of small molecular active layer materials with narrow band gap and strong absorption.This work emphasizes on the following two parts:1.BasedontheIDTderivativeasthedonorunit,2-（3-hexyl-4-oxothiazolidin-2-ylidene）malononitrile as the acceptor unit,by introducing a different amount of alkane thiophene bridge,which can regulate the energy level,coplanarity,absorption spectrum of small molecule acceptor materials to optimize the solar cell devices.The organic solar cells fabricated with the blend of PBDB-T:ITCN,in which ITCN as the acceptor material,PBDB-T as the donor material,demonstrated an open circuit voltage up to 1.25V,PCE reached 2.38%.ITCN was added as the acceptor unit into the PTB7:PC₇₁BM active layer to prepare a ternary blended solar cell device containing a donor unit and two receptor units.Between the ITCN and PTB7 can form complementary absorption and match the energy level,which effectively increase the device JSC and FF.The OSCs based on the blend of PTB7:ITCN:PC₇₁BM show an open-circuit voltage（Voc）of 0.77 V,a short-circuit current density（Jsc）of 16.1 mA cm^-2 and a fill factor（FF）of71%,resulting in a PCE of 8.71%.OSCs cells fabricated using IT-3T-CN:PC₇₁BM blend gave PCE of 1.13%The ternary organic solar cell were also fabricated with PTB7 and IT-3T-CN as donor and PC₇₁BM as acceptor.With 20%ratio of IT-3T-CN ratio,we obtained the highest PCE of 8.61%.2.Based on the IDT derivative as the donor unit and the benzothiadiazole as the acceptor unit,A₁-D-A₂-D based small molecule acceptor material,2-（3-hexyl-4-oxothiazolidin-2-ylidene）malononitrile,wassynthesized.The electrochemical measurement shows that the small molecular acceptor material has an ideal bandgap and has a longerπ-πconjugate length,so thatπ-electrons are more conductive to the distribution along the entire polymer backbone.The ternary organic solar cell with PTB7 as donor and ITBTCN and PC₇₁BM as acceptor showed a stronger absorption from 400-600nm.When ITBTCN ratio was 10%,we obtained the highest PCE is 8.67%.