Design,Synthesis And Characterization Of Semi-Ladder Type Small Molecules And Polymers Based On DPP And IID

High mobility organic/polymeric semiconductors are one of the important fields in organic/polymer optoelectronics materials.Aromatic fused ring compounds have good planarity and small reorganization energy,thus high mobility can be achieved when introduced into conjugated polymers.Based on this concept,a large number of electron rich fused aromatic rings have been synthesized,but ones with electron deficient characteristics are raraly reported for the lack of synthetic method.In view of the above,in this paper,we aim to design and develop novel electron deficient fused aromatic ring units with new efficient synthetic method,and study their applications in conjugated organic/polymeric semiconductors.Main results include:1.Four indeno[1,2-b]thiophene-or benzo[5,6]indeno[1,2-b]thiophene-flanked diketopyrrolopyrrole?DPP?derivatives,i.e.,DPP-PhCO,DPP-PhCN,DPP-NaCO and DPP-NaCN were synthesized efficiently via intramolecular Friedel-Crafts acylation and Knoevenagel condensation.Compare to DPP-Ph,fused ring compounds have longer conjugated skeletons,more rigid planar structuresand lower LUMO energy due to the strong electron withdrawing ability of carbonyl and malononitrile groups.therefor these fused ring compounds displayed better device semiconductor performance.Due to its good crystallinity,DPP-PhCO showed the highest mobility among these compound,with hole mobility of up to 0.052 cm²V^-1s^-1,which was nearly 40 times than that of DPP-Ph.Compound DPP-NaCN,containing malononitrile groups,displayed ambipolar properties in air with hole and electron mobilities of 0.017 and 8.6 x 10^-4 cm²V^-1s^-1,respectively.2.Two acenodithiophe derivatives bridged diketopyrrolopyrroles?DPP?,i.e.,DDPP-PhCO and DDPP-PhCN were developed via intra-molecular Friedel-Crafts acylation and Knoevenagel condensation.And a series of donor-acceptor?D-A?conjugated polymers were synthesized with these two novel units as acceptor.Due to the strongly electron deficient characteristics and rigid planar structures of these two units,all the polymers showed lower bandgap and deep LUMO energy levels.In organic field-effect transistors?OFETs?,polymers contain DDPP-PhCO exhibited ambipolar behavior with the highest hole mobility and electron mobility up to 1.09 cm²V^-1 s^-1 and 0.44 cm² V^-1 s^-1 in air,respectively,outperformanced the parent polymer that did not contain fused ring structure.However,PDNTVT is a hole-dominated material with much poorer OTFT performance with hole and electron mobilities of 0.017 and 8.6x 10^-4 cm²V^-1s^-1,respectively,due to its localized LUMOs,weak crystallinity and completely“face on”orientation backbone.3.Novol semi-ladder type electron deficiency unit based on isoindigo?IID?,i.e.,DIID-PhCO-2Br was developed via intra-molecular Friedel-Crafts acylation.And two D-A conjugated polymers comprising DIID-PhCO as A-unit and bithiophene?DT?or thiophthene?TT?as D-unit were synthesized.Because of low LUMO energy and good delocalization of HOMO and LUMO frontier orbit distribution,two polymers displayed balanced ambipolar behavior of OFETs.Due to completely“edge on”orientation backbone,PDIO-TVT showed higher mobility with hole and electron mobilities of 0.10cm² V^-1 s^-1 and 0.14 cm² V^-1 s^-1,respectively,which was nearlytwo times higher than that of PDIO-DT.