Cheema Hammad, Islam Ashraful, Younts Robert, Gautam Bhoj, Bedja Idriss, Gupta Ravindra Kumar, Han Liyuan, Gundogdu Kenan, El-Shafei Ahmed
Polymer and Color Chemistry Program, North Carolina State University, Raleigh, NC 27695, USA.
Phys Chem Chem Phys. 2014 Dec 28;16(48):27078-87. doi: 10.1039/c4cp04120h.
Here we report two novel amphiphilic Ru(II) heteroleptic bipyridyl complexes, HD-14 and HD-15, compared to previously reported NCSU-10. We have combined the strong electron donor characteristics of carbazole and the hydrophobic nature of different long alkyl chains, C7, C18 and C2 (NCSU-10), tethered to N-carbazole to study their influence on photocurrent, photovoltage and long term stability for dye-sensitized solar cells. Photon harvesting efficiency and electron donating characteristics of carbazole-based ancillary ligands were found to be unaffected by different alkyl chain lengths. However, a slight drop in the Voc of HD-14 and HD-15 was observed compared to that of NCSU-10. It was found by nanosecond flash photolysis transient absorption (TA) measurements that the faster the dye regeneration the higher the photocurrent density response, and the dye regeneration time was found to be 2.6, 3.6, and 3.7 μs for HD-14, HD-15, and N719 dyes, respectively. The difference in the amplitude of the transient absorption (TA) signal of the oxidized dye as measured by femtosecond TA studies is in excellent agreement with the photocurrent generated, which was in the following order HD-14 > HD-15 > N719. Under 1000 h light soaking conditions, HD-15 maintained up to 98% (only 2% loss) of the initial power conversion efficiency compared to 8% loss for HD-14 and 22% loss in the power conversion efficiency for NCSU-10. HD-15 was strikingly stable to light soaking conditions when employed in the presence of an ionic liquid electrolyte, which paves the way for widespread applications of dye-sensitized solar cells with long term stability. The total power conversion efficiency (η) was 9.27% for HD-14 and 9.17% for HD-15 compared to 8.92% for N719.
在此，我们报告了两种新型两亲性钌（II）杂配体联吡啶配合物HD - 14和HD - 15，并与先前报道的NCSU - 10进行了比较。我们将咔唑的强电子供体特性与连接在N - 咔唑上的不同长烷基链（C7、C18和C2（NCSU - 10））的疏水性相结合，以研究它们对染料敏化太阳能电池的光电流、光电压和长期稳定性的影响。发现基于咔唑的辅助配体的光子捕获效率和电子供体特性不受不同烷基链长度的影响。然而，与NCSU - 10相比，观察到HD - 14和HD - 15的开路电压（Voc）略有下降。通过纳秒闪光光解瞬态吸收（TA）测量发现，染料再生越快，光电流密度响应越高，并且发现HD - 14、HD - 15和N719染料的染料再生时间分别为2.6、3.6和3.7微秒。通过飞秒TA研究测量的氧化染料的瞬态吸收（TA）信号幅度差异与产生的光电流非常吻合，顺序为HD - 14 > HD - 15 > N719。在1000小时光照浸泡条件下，HD - 15保持了高达98%（仅2%损失）的初始功率转换效率，相比之下，HD - 14损失了8%，NCSU - 10的功率转换效率损失了22%。当在离子液体电解质存在下使用时，HD - 15对光照浸泡条件具有显著的稳定性，这为具有长期稳定性的染料敏化太阳能电池的广泛应用铺平了道路。HD - 14的总功率转换效率（η）为9.27%，HD - 15为9.17%，而N719为8.92%。
