Evolution of Structure, Optoelectronic Properties, and Device Performance of Polythiophene:Fullerene Solar Cells During Thermal Annealing
Evolution of Structure, Optoelectronic Properties, and Device Performance of Polythiophene:Fullerene Solar Cells During Thermal Annealing
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DOI：
10.1002/adfm.201002300
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发表时间：
2011-04
影响因子：
19
通讯作者：
Tao Wang;Andrew J Pearson;David G Lidzey;Richard A. L. Jones
中科院分区：
文献类型：
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作者：
Tao Wang;Andrew J Pearson;David G Lidzey;Richard A. L. Jones
利用椭偏光谱技术研究了聚（3‐己基噻吩）（P3HT）和[6,6]‐苯基C61‐丁酸甲酯（PCBM）光伏薄膜共混物在热处理过程中的结构和光电性能的演变。研究确定了四个不同的过程：超过混合物玻璃化转变温度的残余溶剂的蒸发，通过自旋铸造形成的非平衡分子构象的松弛，P3HT和PCBM组分的结晶，以及P3HT和PCBM结构域的相分离。在150°C下退火10至60分钟的器件显示出约4.0%的平均功率转换效率。我们发现P3HT/PCBM返回室温的速率在决定器件效率方面比等温退火过程的持续时间更重要。我们得出结论，薄膜从退火温度到室温的快速淬火阻碍了P3HT的结晶，并且可以捕获非平衡形态状态。这种状态显然会影响器件的短路电流、填充系数，从而影响运行效率。
We use spectroscopic ellipsometry to study the evolution of structure and optoelectronic properties of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) photovoltaic thin film blends upon thermal annealing. Four distinct processes are identified: the evaporation of residual solvent above the glass transition temperature of the blend, the relaxation of non‐equilibrium molecular conformation formed through spin‐casting, the crystallization of both P3HT and PCBM components, and the phase separation of the P3HT and PCBM domains. Devices annealed at 150 °C for between 10 and 60 min exhibit an average power conversion efficiency of around 4.0%. We find that the rate at which the P3HT/PCBM is returned to room temperature is more important in determining device efficiency than the duration of the isothermal annealing process. We conclude that the rapid quenching of a film from the annealing temperature to room temperature hampers the crystallization of the P3HT and can trap non‐equilibrium morphological states. Such states apparently impact on device short circuit current, fill factor and, thus, operational efficiency.