고분자 태양 전지를 위한 플루오렌 기반의 고분자 전해질의 합성

Abstract

A series of conjugated polyelectrolytes (CPEs) based on fluorene named 6,6-(2-phenyl-9H-fluorene-9,9-diyl) bis(N,N,N-trimethylhexan-1-aminium) bromide (PFB-Br), 6,6'-(2-(thiophene-2-yl)-9H-fluorene-9,9-diyl) bis(N,N,N-trimethylhexan-1-aminium) bromide (PFT-Br), and 6,6'-(2-([2,2'-bithiophen]-5-yl)-9H-fluorene-9,9-diyl) bis(N,N,N-trimethylhexan-1-aminium) bromide (PF2T-Br) were synthesized and applied as the interlayer to investigate how the backbone structure influence the photovoltaic properties. The ionic functionality of the CPE accumulates on the ZnO surface, owing to the existing interactions between the ionic groups and the ZnO. The CPE backbone is directed away from the ZnO surface, indicating the spontaneous organization of CPEs occurs during the spin coating process. Subsequently, occurring a redistribution of the internal electric field in the device and the formation of permanent dipole through the spontaneous reorientation of the ionic groups and backbone. However, incorporation of the electron-rich moiety, thiophene, or bithiophene, in the polymer backbone interfere with the electron transport from the active layer to the cathode. As a result, the power conversion efficiency (PCE) of polymer with thiophene and bithiophene backbone structure was decreased compare with PFB-Br, which has electron-affinity property than PFT-Br, and PF2T-Br.