Relating the open-circuit voltage to interface molecular properties of donor:acceptor bulk heterojunction solar cells
Relating the open-circuit voltage to interface molecular properties of donor:acceptor bulk heterojunction solar cells
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DOI：
10.1103/physrevb.81.125204
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发表时间：
2010-03-01
影响因子：
3.7
通讯作者：
Manca, Jean V.
中科院分区：
文献类型：
--
作者：
Vandewal, Koen;Tvingstedt, Kristofer;Manca, Jean V.
聚合物：富勒烯体异质结太阳能电池的开路电压（V（oc））由聚合物和富勒烯之间的界面电荷转移（CT）状态决定。傅立叶变换光电流光谱和电致发光光谱的几种聚合物：富勒烯共混物被用来提取相关的界面分子参数。推导出了将这些性质与V（oc）联系起来的解析表达式，并证明其对光伏器件是有效的，所述光伏器件包括三种常用的与富勒烯衍生物[6，6]-苯基-C61-丁酸甲酯（PCBM）共混的共轭聚合物。V（oc）与CT态E（CT）的能量成比例。E（CT）和qV（oc）之间的能量损失q Δ V在接近0 K时消失。它与T成线性关系，与光照强度成几何关系。此外，可以通过降低聚合物和富勒烯之间的电子耦合或通过降低非辐射复合速率来降低q Δ V。对于所研究的设备，我们发现在室温下和在太阳光照条件下，类似于0.6 eV的损耗q Δ V，其中类似于0.25 eV是由于通过CT状态的辐射复合，类似于0.35 eV是由于非辐射复合。
The open-circuit voltage (V(oc)) of polymer:fullerene bulk heterojunction solar cells is determined by the interfacial charge-transfer (CT) states between polymer and fullerene. Fourier-transform photocurrent spectroscopy and electroluminescence spectra of several polymer:fullerene blends are used to extract the relevant interfacial molecular parameters. An analytical expression linking these properties to V(oc) is deduced and shown to be valid for photovoltaic devices comprising three commonly used conjugated polymers blended with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). V(oc) is proportional to the energy of the CT states E(CT). The energetic loss q Delta V between E(CT) and qV(oc) vanishes when approaching 0 K. It depends linearly on T and logarithmically on illumination intensity. Furthermore q Delta V can be reduced by decreasing the electronic coupling between polymer and fullerene or by reducing the nonradiative recombination rate. For the investigated devices we find a loss q Delta V of similar to 0.6 eV at room temperature and under solar illumination conditions, of which similar to 0.25 eV is due to radiative recombination via the CT state and similar to 0.35 eV is due to nonradiative recombination.