Nongeminate and Geminate Recombination in PTB7: PCBM Solar Cells
Nongeminate and Geminate Recombination in PTB7: PCBM Solar Cells
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DOI：
10.1002/adfm.201302134
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发表时间：
2014-03-01
影响因子：
19
通讯作者：
Deibel, Carsten
中科院分区：
文献类型：
--
作者：
Foertig, Alexander;Kniepert, Juliane;Deibel, Carsten
对聚[[4，8-双[（2-乙基己基）氧基]苯并[1，2-B：4，5-b ']二噻吩-2，6-二基] [3-氟-2-[（2-乙基己基）羰基]噻吩并[3，4-B]噻吩二基]]（PTB 7）：[6，6]-苯基-C71-丁酸（PC 71 BM）本体异质结太阳能电池应用瞬态光电压（TPV）、电压依赖性电荷提取（CE）和时间延迟收集场（TDCF）测量的组合以分析光伏性能的限制。器件由纯氯苯（CB）溶液处理，并使用1，8-二碘辛烷（DIO）作为共溶剂优化子集。器件性能的巨大变化进行了讨论相对于占主导地位的损失过程。虽然在CB溶液处理的器件中观察到严重的成对和非成对重组，但DIO的使用促进了有效的极化子对解离并使成对重组最小化。因此，根据开路条件下确定的电荷载流子衰减速率和电压依赖性电荷载流子密度n（V），仅具有DIO的样品的非对数损失电流J（loss）使得能够在整个操作电压范围内重建电流/电压（j/V）特性。Geminate和nongeminate的损失被认为是描述的J/V响应的电池制备没有添加剂，但导致一个明显高估的设备性能。测量和重建的J/V特性之间的偏差归因于纯富勒烯相的孤立域中的陷阱电荷。
A combination of transient photovoltage (TPV), voltage dependent charge extraction (CE), and time delayed collection field (TDCF) measurements is applied to poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-phenyl-C71-butyric acid (PC71BM) bulk heterojunction solar cells to analyze the limitations of photovoltaic performance. Devices are processed from pure chlorobenzene (CB) solution and a subset is optimized with 1,8-diiodooctane (DIO) as co-solvent. The dramatic changes in device performance are discussed with respect to the dominating loss processes. While in the devices processed from CB solution severe geminate and nongeminate recombination is observed, the use of DIO facilitates efficient polaron pair dissociation and minimizes geminate recombination. Thus, from the determined charge carrier decay rate under open circuit conditions and the voltage dependent charge carrier densities n(V), the nongeminate loss current J(loss) of the samples with DIO alone enables the reconstruction of the current/voltage (j/V) characteristics across the whole operational voltage range. Geminate and nongeminate losses are considered to describe the j/V response of cells prepared without additive, but lead to a clearly overestimated device performance. The deviation between measured and reconstructed j/V characteristics is attributed to trapped charges in isolated domains of pure fullerene phases.