Reducing Voltage Losses in Cascade Organic Solar Cells while Maintaining High External Quantum Efficiencies
Reducing Voltage Losses in Cascade Organic Solar Cells while Maintaining High External Quantum Efficiencies
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DOI：
10.1002/aenm.201700855
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发表时间：
2017-11-08
影响因子：
27.8
通讯作者：
Vandewal, Koen
中科院分区：
文献类型：
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作者：
Nikolis, Vasileios C.;Benduhn, Johannes;Vandewal, Koen
高光子能量损失限制了有机太阳能电池（OSC）的开路电压（V-OC）和功率转换效率。在这项工作中，提出了一种优化路线，通过减少供体（D）和受体（A）之间的界面面积来增加V-OC。该优化路线涉及级联器件结构，其中在α-六噻吩之间引入不连续夹层（α-6T）（D）和氯硼亚萘（SubNc）（A）将α-6T/SubNc/SubPc无富勒烯级联OSC的V-OC从0.98 V增加到1.16 V。一个接口。通过精确测量所研究的OSC的光学带隙（E-opt）和电荷转移态（E-CT）的能量，对整体电压损耗进行了详细的分析。获得了0.58 eV的E-opt - qV（OC）损失，这是对OSC观察到的最低损失之一。最重要的是，对于V-OC优化的器件，尽管电荷分离的最小驱动力小于10 meV，但低能（700 nm）外量子效率（EQE）峰值仍高达79%。这项工作表明，在有机光伏器件中，低电压损耗可以与高EQE相结合。
High photon energy losses limit the open-circuit voltage (V-OC) and power conversion efficiency of organic solar cells (OSCs). In this work, an optimization route is presented which increases the V-OC by reducing the interfacial area between donor (D) and acceptor (A). This optimization route concerns a cascade device architecture in which the introduction of discontinuous interlayers between alpha-sexithiophene (alpha-6T) (D) and chloroboron subnaphthalocyanine (SubNc) (A) increases the V-OC of an alpha-6T/SubNc/SubPc fullerene-free cascade OSC from 0.98 V to 1.16 V. This increase of 0.18 V is attributed solely to the suppression of nonradiative recombination at the D-A interface. By accurately measuring the optical gap (E-opt) and the energy of the charge-transfer state (E-CT) of the studied OSC, a detailed analysis of the overall voltage losses is performed. E-opt - qV(OC) losses of 0.58 eV, which are among the lowest observed for OSCs, are obtained. Most importantly, for the V-OC-optimized devices, the low-energy (700 nm) external quantum efficiency (EQE) peak remains high at 79%, despite a minimal driving force for charge separation of less than 10 meV. This work shows that low-voltage losses can be combined with a high EQE in organic photovoltaic devices.