"Solvent annealing" effect in polymer solar cells based on poly(3-hexylthiophene) and methanofullerenes
"Solvent annealing" effect in polymer solar cells based on poly(3-hexylthiophene) and methanofullerenes
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DOI：
10.1002/adfm.200600624
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发表时间：
2007-07-09
影响因子：
19
通讯作者：
Yang, Yang
中科院分区：
文献类型：
--
作者：
Li, Gang;Yao, Yan;Yang, Yang
本文系统地研究了基于区域规整聚(3-己基噻吩基)：[6，6]-苯基C-61-丁酸甲酯的聚合物在太阳电池中的自组织行为，研究了旋涂时间t(S)(20-80 S)对旋涂时间t(A)的影响。旋涂时间t(A)是旋涂后溶剂干燥所需的时间。用光致发光光谱、紫外-可见吸收光谱、原子力显微镜和掠入射X射线衍射仪对共混膜进行了表征。结果表明，当t(A)大于1min时，膜中RR-P3HT的pi共轭结构得到最佳发展(t(S)类似于50 S)。对于t(S)<；50 S，相应聚合物太阳电池的短路电流J(Sc)和功率转换效率(Pce)都呈现平台区，而对于50<；t(S)<；55 S，J(Sc)和Pce值显著降低，这表明在这个时间窗口内聚合物的有序性发生了重大变化。对于具有高度有序的pi-P3HT结构的薄膜，PCE从3.6%下降到较少有序的薄膜的1.2%。GIXRD结果证实了聚合物的有序性发生了变化。特别是，有序程度较低的太阳能电池的入射光电子转换效率谱在总体量级和长波响应方面都有明显的损失。还研究了不同浓度的PCBM(PCBM浓度在25~67wt%之间)对器件的溶剂退火效应。在“溶剂退火法”条件下，即使在67wt%的PCBM负载量下，聚合物也是有序的。开路电压(V-OC)还受聚合物的有序性和有源层中PCBM的载入量的影响。
The self organization of the polymer in solar cells based on regioregular poly(3-hexylthiophene) (RR-P3HT):[6,6]-phenyl C-61-butyric acid methyl ester (PCBM) is studied systematically as a function of the spin-coating time t(s) (varied from 20-80 s), which controls the solvent annealing time t(a), the time taken by the solvent to dry after the spin-coating process. These blend films are characterized by photoluminescence spectroscopy, UV-vis absorption spectroscopy, atomic force microscopy, and grazing incidence X-ray diffraction (GIXRD) measurements. The results indicate that the pi-conjugated structure of RR-P3HT in the films is optimally developed when t(a) is greater than 1 min (t(s) similar to 50 s). For t(s) < 50 s, both the short-circuit current (J(SC)) and the power conversion efficiency (PCE) of the corresponding polymer solar cells show a plateau region, whereas for 50 < t(s) < 55 s, the J(SC) and PCE values are significantly decreased, suggesting that there is a major change in the ordering of the polymer in this time window. The PCE decreases from 3.6% for a film with a highly ordered pi-conjugated structure of RR-P3HT to 1.2% for a less-ordered film. GIXRD results confirm the change in the ordering of the polymer. In particular, the incident photon-to-electron conversion efficiency spectrum of the less-ordered solar cell shows a clear loss in both the overall magnitude and the long-wavelength response. The solvent annealing effect is also studied for devices with different concentrations of PCBM (PCBM concentrations ranging from 25 to 67 wt%). Under "solvent annealing" conditions, the polymer is seen to be ordered even at 67 wt% PCBM loading. The open-circuit voltage (V-OC) is also affected by the ordering of the polymer and the PCBM loading in the active layer.