Two pairs of A-D-A molecules have been synthesized with fluorene and benzodithiophene as the central donor subunits and terminal BODIPY units, functionalized with either a 4-methylphenyl or 4-trifluoromethylphenyl group at the meso position. The effect of the para substituent of the meso phenyl group on the photophysical properties of these molecules is studied through steady state absorption and fluorescence spectroscopy as well as femtosecond transient absorption and time resolved fluorescence spectroscopy techniques. Applicability of these molecules as donors in solution processed solar cell active layers was investigated through time resolved microwave conductivity measurements on blends with PC₆₀BM acceptor, which shows a varying yield of charge transfer with choice of substituent. Transient absorption spectroscopy is then employed to investigate the role of the 4-trifluoromethylphenyl group in altering the efficiency of charge transfer from these A-D-A molecules to PC₆₀BM. The results show a consistent picture of picosecond charge transfer and a component of a few hundred ps geminate recombination that results in a small yield of long-lived free charges optimized for the methylphenyl derivatives.

已经合成了两对ADA分子，它们以芴和苯并二噻吩为中心供体亚基和末端BODIPY单元，并在内消旋位置被4-甲基苯基或4-三氟甲基苯基官能化。通过稳态吸收和荧光光谱以及飞秒瞬态吸收和时间分辨荧光光谱技术研究了内消旋苯基的对位取代基对这些分子的光物理性质的影响。通过在PC ₆₀混合物中进行时间分辨的微波电导率测量，研究了这些分子作为供体在溶液处理的太阳能电池活性层中的适用性BM受体，随着取代基的选择，其电荷转移的收率变化。然后采用瞬态吸收光谱法研究了4-三氟甲基苯基在改变电荷从这些ADA分子转移至PC ₆₀ BM的效率中的作用。结果显示了皮秒电荷转移的一致性图片，并且数百ps的新生化合物发生了重组，导致针对甲基苯基衍生物进行优化的长寿命游离电荷的收率很小。