| Over the last years, there has been an increasing interest in polymeric solar cells(PSCS). Conjugated polymers are now recognized as the emerging semiconductors due to their low cost, ease of processing and flexibility. However, compared to inorganic materials, conjugated polymers have some serious limitations for photovoltaic materials because of their relatively low mobility of charge carriers and their narrow absorption bands which have poor coverage with solar spectrum.Design and synthesis of new polymer are of great theoretical and practical value.In this thesis, two D-A type conjugated polymers composing of benzothiadiazole,carbazole and thieno[3,4-c]pyrrol-4,6-dione,respectively,were synthesized,and applied to the PSCS.The photophysical and electrochemical properties of the polymers were investigated,and performance of PSC based above mentioned polymers was studied.An Donor-Accepter type conjugated polymer P1 comprising 2,7-carbazole and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzo-[c][1,2,5]-thia zole was successfully synthesized by Suzuki cross coupling. The polymer was characterized using'HNMR. The photophysical and electrochemical properties of the polymer were investigated.The results demonstrate that the copolymer P1 has good thermal stability with thermal decomposition temperation at 305℃.The copolymer P1 has a broad absorption from 300nm to 660 nm and its optional band gap was estimated to be 1.88eV. The HOMO level(ionization potential, IP)of -5.23 eV and the LUMO level(electron affinities, EA) of -3.59 eV was obtained from the cyclic voltammetry curve. Bulk heterojunction solar cells fabricated from composite films of P1 as electron donor and PCBM as electron acceptor shows power conversion efficiencies 0.92% with open-circuit voltage 0.88V,short-circuit current density of 2.04 mA·cm-2 and fill factor of 0.51 under AM 1.5 solar simulator (100mW·cm-2).A new Donor-Accepter type conjugated polymer P2 comprising 2,7-carbazole and thieno[3,4-c]pyrrol-4,6-dione was synthesized by Suzuki cross coupling. The polymer was characterized using 1HNMR. The photophysical and electrochemical properties of the polymer were investigated.The results demonstrate that the copolymer P2 has good thermal stability with thermal decomposition temperation at 350℃.The copolymer P2 has a broad absorption from 300nm to 550 nm and its optional bad gap was estimated to be 2.17 eV.The HOMO level(ionization potential, IP) of -5.46 eV and the LUMO level(electron affinities, EA) of -3.32 eV was obtained from the cyclic voltammetry curve. Bulk heterojunction solar cells fabricated from composite films of P2 as electron donor and PCBM as electron acceptor shows power conversion efficiencies 0.52% with open-circuit voltage 0.88V,short-circuit current density of 1.17 mA·cm-2 and fill factor of 0.51 under AM 1.5 solar simulator(100mW/cm2).2,5-Dibromo-thieno[3,2-b]thiophene(D2) and 2,5-dibromo-3,6-diotyloxy-thieno[3,2-b]thiophene(D3) were synthesized as electrons.2,5-dibromo-3,4-ethyleneduoxythiophene(D4) was also desighed and synthesized as electron donor.The monomer reactions were studied which is the basis of preparing high-performance solar cells by designing and synthesizing new polymer photovoltaic materials. |
