Temperature-Dependent Charge-Transfer-State Absorption and Emission Reveal the Dominant Role of Dynamic Disorder in Organic Solar Cells
Temperature-Dependent Charge-Transfer-State Absorption and Emission Reveal the Dominant Role of Dynamic Disorder in Organic Solar Cells
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DOI：
10.1103/physrevapplied.15.064009
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发表时间：
2021-06-03
影响因子：
4.6
通讯作者：
Deibel, Carsten
中科院分区：
文献类型：
--
作者：
Goehler, Clemens;Saladina, Maria;Deibel, Carsten
有机光电器件中供电子域和接受电子域界面上电荷转移态的能量格局对其性能至关重要。核心问题——如静态能量紊乱和振动效应的作用——仍在争论中。本研究深入分析了小分子富勒烯共混物器件中CT态光谱吸收和发射特性随温度变化的展宽。我们证实了光电外量子效率与电致发光之间的电光互易关系的有效性，使我们能够在实验中验证器件温度。验证的温度允许我们将实验数据与多个模型拟合，并将提取的CT状态能量与相应的0 K开路电压极限进行比较。研究结果表明，吸收和发射特征通常不对称，主要是温度激活的展宽（振动）效应，而不是静态无序。
The energetic landscape of charge-transfer (CT) states at the interface of electron donating and electron accepting domains in organic optoelectronic devices is crucial for their performance. Central ques-tions-such as the role of static energetic disorder and vibrational effects-are under ongoing dispute. This study provides an in-depth analysis of temperature-dependent broadening of the spectroscopic absorption and emission features of CT states in devices with small molecule-fullerene blends. We confirm the valid -ity of the electro-optical reciprocity relation between the photovoltaic external quantum efficiency and electroluminescence, enabling us to validate the device temperature during the experiment. The validated temperature allows us to fit our experimental data with several models, and compare extracted CT state energies with the corresponding open-circuit voltage limit at 0 K. Our findings reveal that the absorp-tion and emission characteristics are usually not symmetric, and dominated by temperature-activated broadening (vibrational) effects instead of static disorder.