Energy Upconversion via Triplet Fusion in Super Yellow PPV Films Doped with Palladium Tetraphenyltetrabenzoporphyrin: a Comprehensive Investigation of Exciton Dynamics
Energy Upconversion via Triplet Fusion in Super Yellow PPV Films Doped with Palladium Tetraphenyltetrabenzoporphyrin: a Comprehensive Investigation of Exciton Dynamics
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DOI：
10.1002/adfm.201201284
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发表时间：
2013-01-21
影响因子：
19
通讯作者：
Monkman, Andy
中科院分区：
文献类型：
--
作者：
Jankus, Vygintas;Snedden, Edward W.;Monkman, Andy
关于高效聚合物太阳能电池技术的发展的关键问题之一是缺乏在近红外（NIR）区域吸收的可行材料。这可以通过使用三重态聚变（TF）将来自NIR的能量上转换为可见光来解决，其中附加层与太阳能电池分开制造并沉积在顶部。理论上可以获得50%的经由TF效率的最大上转换（UC）。这里，证明了在掺杂有4%钯（内消旋-四苯基-四苯并卟啉）（PdTPBP）敏化剂的市售聚（对亚苯基亚乙烯基）共聚物超黄（SY）的膜中，可以实现6%的UC效率。通过使用飞秒和纳秒光谱，它表明，主要的UC效率损失机制是由于三重态猝灭PdTPBP聚集体。测定了PdTPBP的系间穿越速率常数为1.8 × 10 ~（11）s ~（-1），PdTPBP与SY的三重态能量转移速率常数为10 ~（9）s ~（-1）。PdTPBP聚集体中的淬灭可以解释76- 99%范围内的三重态浓度损失。因此，防止NIR至可见光上转换膜中的敏化剂聚集是至关重要的，并且可能导致膜中UC效率的显著增加。
One of the key issues concerning the development of efficient polymer solar cell technology is the lack of viable materials which absorb in the near-infrared (NIR) region. This could be resolved by up-converting energy from the NIR into visible using triplet fusion (TF) with an additional layer that is fabricated separately from the solar cell and deposited on top. Theoretically a maximum upconversion (UC) via TF efficiency of 50% could be obtained. Here, it is demonstrated that in a film of commercially available poly(para-phenylene vinylene) copolymer super yellow (SY) doped with 4% palladium(meso-tetraphenyl-tetrabenzoporphyrin) (PdTPBP) sensitizer, an UC efficiency of 6% can be achieved. By using femtosecond and nanosecond spectroscopies it is shown that the main UC efficiency loss mechanism is due to triplet quenching in PdTPBP aggregates. The PdTPBP intersystem crossing rate constant is determined to be 1.8 X 1011 s-1 and the triplet energy transfer rate constant from PdTPBP to SY to be 109 s-1. Quenching in PdTPBP aggregates can account for a triplet concentration loss in the range of 76-99%. As such, preventing sensitizer aggregation in NIR-to-visible upconverting films is crucial and may lead to substantial increase of UC efficiencies in films.