Influence of Ion Induced Local Coulomb Field and Polarity on Charge Generation and Efficiency in Poly(3-Hexylthiophene)-Based Solid-State Dye-Sensitized Solar Cells
Influence of Ion Induced Local Coulomb Field and Polarity on Charge Generation and Efficiency in Poly(3-Hexylthiophene)-Based Solid-State Dye-Sensitized Solar Cells
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DOI：
10.1002/adfm.201100048
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发表时间：
2011-07-08
影响因子：
19
通讯作者：
Snaith, Henry J.
中科院分区：
文献类型：
--
作者：
Abrusci, Agnese;Kumar, R. Sai Santosh;Snaith, Henry J.
染料敏化太阳能电池（DSSC）是将光转换为电能的现实选择。混合架构为器件优化提供了一个庞大的材料库，包括各种金属氧化物，有机和无机敏化剂，分子，聚合物和电解质空穴传输材料。为了进一步提高固态染料敏化太阳能电池的效率，最近的注意力集中在使用光吸收聚合物如聚（3-己基噻吩）（P3 HT）来代替更常用的“透明的”2，2 '，7，7'-四-（N，N-二-对甲氧基苯胺）9，9 '螺-二芴（螺-OMe），以增强薄膜内的光吸收。与基于螺环-OMeCl 4的固态DSSC的情况一样，基于P3 HT的器件在添加双（三氟甲基磺酰基）酰亚胺锂盐（Li-TFSI）的情况下显著改善，尽管这些添加剂在固态DSC中的确切作用尚未澄清。在这里，我们提出了一个彻底的研究的影响，锂TFSI在P3 HT为基础的固态DSSC纳入吲哚为基础的有机敏化剂称为D102。采用超快瞬态吸收和连续波发射光谱与电子测量，我们证明了一个微调的充满活力的景观的活性细胞成分的局部库仑场诱导的离子。这增加了染料上激发态的电荷转移性质，显著加速了电子注入TiO 2。我们证明，这种离子的影响，激发态能量是增强电荷产生的主要原因，与添加离子添加剂。二氧化钛导带的相对位置的加深，这以前被认为是在染料敏化太阳能电池中增加锂盐的电荷产生的原因，似乎是次要的在这个系统中。
Dye-sensitized solar cells (DSSC) are a realistic option for converting light to electrical energy. Hybrid architectures offer a vast materials library for device optimization, including a variety of metal oxides, organic and inorganic sensitizers, molecular, polymeric and electrolytic hole-transporter materials. In order to further improve the efficiency of solid-state dye-sensitized solar cells, recent attention has focused on using light absorbing polymers such as poly(3-hexylthiophene) (P3HT), to replace the more commonly used "transparent" 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)9,9'spiro-bifluorene (spiro-OMeTAD), in order to enhance the light absorption within thin films. As is the case with spiro-OMeTAD based solid-state DSSC, the P3HT-based devices improve significantly with the addition of lithium bis(trifluoromethylsulfonyl) imide salts (Li-TFSI), although the precise role of these additives has not yet been clarified in solid-state DSCs. Here, we present a thorough study on the effect of Li-TFSI in P3HT based solid-state DSSC incorporating an indolene-based organic sensitizer termed D102. Employing ultrafast transient absorption and cw-emission spectroscopy together with electronic measurements, we demonstrate a fine tuning of the energetic landscape of the active cell components by the local Coulomb field induced by the ions. This increases the charge transfer nature of the excited state on the dye, significantly accelerating electron injection into the TiO2. We demonstrate that this ionic influence on the excited state energy is the primary reason for enhanced charge generation with the addition of ionic additives. The deepening of the relative position of the TiO2 conduction band, which has previously been thought to be the cause for enhanced charge generation in dye sensitized solar cells with the addition of lithium salts, appears to be of minor importance in this system.