A series of novel single and double branched carbazole-based red-absorbing cationic dyes without (CSI and CDI) and with (CST and CDT) a thiophene spacer have been synthesized for p-type dye-sensitized solar cells (p-DSSCs). The introduction of the red-absorbing cationic acceptor/thiophene spacer led to the broadening and bathochromic shift of the absorption maxima from an onset of 600 nm for CSI to 800 nm for CDT as well as improved molar absorptivity. The introduction of the double branching/thiophene spacer lowered the lowest unoccupied molecular orbital (LUMO) levels of CDI, CST, and CDT, making their potentials more positive than that of CSI. Among these, the double branched CDI exhibited the highest conversion efficiency of 0.112%. Furthermore, all of the dyes examined outperformed the standard C343 dye (0.062%), measured under similar fabrication conditions. Despite the decreased photovoltaic performance as a result of the introduction of the thiophene spacer, overall, the double branched dyes exhibited better interfacial charge transfer that led to higher J_SC and V_OC values compared to those of singly branched dyes. Electrochemical impedance spectroscopy analysis showed that double branched dyes have much lower charge transfer resistance and increased hole lifetime than single branched dyes. Density functional theory (DFT) and time-dependent DFT calculations were performed to theoretically characterize the optical and electrochemical properties of the synthesized dyes.

已经为p型染料敏化太阳能电池合成了一系列新颖的单支和双支咔唑基红色吸收阳离子染料，不含（CSI和CDI），不含（CST和CDT）噻吩间隔基（p-DSSC）。吸收红光的阳离子受体/噻吩间隔基的引入导致吸收最大值从CSI的600 nm起始到CDT的800 nm扩展和红移，并提高了摩尔吸收率。双支/噻吩间隔基的引入降低了CDI，CST和CDT的最低空位分子轨道（LUMO）水平，使其电势比CSI更强。其中，双支CDI的转化效率最高，为0.112％。此外，在相似的制造条件下测得的所有染料均优于标准C343染料（0.062％）。尽管由于噻吩间隔基的引入导致光伏性能下降，但总体而言，与单支链染料的_SC和V _OC值相比。电化学阻抗谱分析表明，双支化染料比单支化染料具有更低的电荷转移电阻和更长的空穴寿命。进行密度泛函理论（DFT）和与时间有关的DFT计算，以从理论上表征合成染料的光学和电化学性质。