Research On Synthesis And Properties Of D'(A-D)_n Type Organic Small Molecule Donor Materials Based On Benzo[4,5]thieno[2,3-b]indole Used As Terminal Group

Along with the increasingly serious environmental pollution and fossil energy shortage,the development of sustainable,clean and pollution-free new energy is imminent.As organic solar cells have very desirable properties,including low cost of materials,high-throughput roll-to-roll production,mechanical flexibility and light weight,they have attracted more and more attention recently.In this dissertation,we systematically introduced the development of OPVs and their working principles,as well as their dornor and acceptor materials in OPVs.In order to solve the existing problems of OPVs such as the relatively low power conversion efficience(PCE)that can't meet the demand of commercial production,less variety of high-performance donor materials,a seriers of donor(D)-acceptor(A)type OSMs based on the benzo[4,5]thieno[2,3-b]indole(BTI)and diketopyrrolopyrrole(DPP)were designed and synthesized.Their molecular structures were characterized.Their thermal stability,and photoelectric property,charge transport properties,as well as their photovoltaic performance in BHJ-OPVs were systematically investigated.The relationship among molecular structures and these performances were preliminarily revealed.The key studies are listed as follows:1)Four low band-gap OSMs of D-A-D types used as photovoltaic donor materials were designed and synthesized,in which carbazole(Cz)and 9-BTI were used as terminal D groups,DPP derivatives and benzothiadiazole(BT)were used as as central A groups.The effect of the different kinds of D,A unit building small molecules on photovoltaic performance was systematically studied.D unit the matching of A unit was discussed and the effect of the terminal unit ring expanding on the performance of small molecular photovoltaic devices was discussed.It was found that SM of DPP-9-2BTI with DPP and 9-BTI as central and terminal unit,exhibited better photovoltaic properties.The maximum power conversion efficiency(PCE)of1.72% with an open circuit voltage(Voc)of 0.71 V,a short circuit current(Jsc)of7.14mA/cm2 and a fill factor(FF)of 33.78% was obtained in the DPP-9-2BTI-based BHJ-OPVs.2)Two OSMs of D-A-D?-A-D types used as photovoltaic donor materials were designed and synthesized,in which thiophene and bithiophene were used as central D?groups,DPP were used as A groups,9-BTI as terminal D groups.The effect of the molecular configuration and the conjugate chain extension of SMs on photovoltaic performance was investigated.It was shown that the SM of T(DPP-9-BTI)2 based on thiophene,DPP and 9-BTI exhibited better photovoltaic performance in their BHJ-OPVs.The maximum PCE of 3.02% with Voc of 0.52 V,Jsc of 10.41 mA/cm2 and FF of 55.8%,was obtaind in the T(DPP-9-BTI)2-based BHJ-OPVs.3)Three OSMs of D-A-D?-A-D types used as photovoltaic donor materials were designed and synthesized,in which one-dimensional benzodithiophene(BDT),two-dimensional benzodithiophene(DBDT)and thienothiophene(TT)were used as central D? groups,DPP was used as A groups,9-BTI as terminal D groups.The effect of the different central D? groups of SMs on photovoltaic performance was investigated.It was shown that the SM of BDT(DPP-9-BTI)2 based on BDT,DPP and9-BTI exhibited better photovoltaic performance in their BHJ-OPVs.The maximum PCE of 3.52% with Voc of 0.55 V,Jsc of 11.50 m A/cm2 and FF of 54.51%,was obtaind in the BDT(DPP-9-BTI)2-based BHJ-OPVs.4)OSMs of D-A-D and D-A-D?-A-D types OSMs used as photovoltaic donor materials were designed and synthesized,in which DPP was used as A groups and9-BTI as terminal D groups.The effect of the changing substituted position of terminals for SMs on photovoltaic performance was investigated.It was shown that the SM of BDT(DPP-8-BTI)2 based on BDT,DPP and 8-BTI exhibited best photovoltaic performance in their BHJ-OPVs.The maximum PCE of 4.80% with Voc of 0.64 V,Jsc of 11.91 mA/cm2 and FF of 63.4%,was obtaind in the BDT(DPP-9-BTI)2-based BHJ-OPVs.