| 초록 |
A series of small molecule consist of Quinoxaline and Benzodithiophene ( BDT ) had different length of alkyl side chain. These small molecule displayed λmax 468 ~ 475nm in solution and 536 ~ 540nm in film state. These small molecule had same backbone excluding alkyl side chain. For the reason, these small molecule had similar electrochemical properties. On the other hand, they indicated slightly different in HOMO energy level. The ethyl-hexyl-substituted BDT ((EH-BDT(DTDFDDoQx)2, EH-BDT(DTDFDHexQx)2) had a deeper HOMO energy value ( -5.38, -5.35 ) than the octyl-substituted BDT ((Oct-BDT(DTDFDDoQx)2, Oct-BDT(DTDFDHexQx)2). LUMO energy value ( -3.21, -3.22, -3.17 and -3.19) was similar because of these small molecule had same backbone. As a result, EH-BDT(DTDFDDoQx)2 had long alkyl side chain ( dodecyl ) in Quinoxaline unit and bulky side chain ( ethyl-hexyl ) in BDT unit approached highest PCE of 0.62% in series. |
