17.1% Efficient Single-Junction Organic Solar Cells Enabled by n-Type Doping of the Bulk-Heterojunction
17.1% Efficient Single-Junction Organic Solar Cells Enabled by n-Type Doping of the Bulk-Heterojunction
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DOI：
10.1002/advs.201903419
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发表时间：
2020-02-13
期刊：
影响因子：
15.1
通讯作者：
Anthopoulos, Thomas D.
中科院分区：
文献类型：
--
作者：
Lin, Yuanbao;Firdaus, Yuliar;Anthopoulos, Thomas D.
分子掺杂通常用于有机半导体中以调节其（光）电子性质。然而，尽管其多功能性，其在有机光致发光（OPV）中的应用仍然受限，并且仅限于p型掺杂剂。为了控制OPV的本体异质结（BHJ）内的电荷传输，将n型掺杂剂苄基紫精（BV）掺入由供体聚合物PM 6和小分子受体IT-4F组成的BHJ中。发现当添加0.004wt%BV时，电池的功率转换效率（PCE）从13.2%增加到14.4%。光活性材料和器件的分析表明，BV同时作为BHJ的n型掺杂剂和微结构改性剂。在最佳BV浓度下，这些协同效应导致平衡的空穴和电子迁移率、更高的吸收系数和BHJ内增加的电荷载流子密度，同时显著延长电池的保质期。的n型掺杂策略被施加到五个额外的BHJ系统，获得同样显着的性能改善。特别感兴趣的OPV基于三元PM 6：Y 6：PC 71 BM：BV（0.004重量%）共混物，其获得17.1%的最大PCE。n掺杂策略的有效性突出了基于NFA的OPV中的电子传输是一个关键问题。
Molecular doping is often used in organic semiconductors to tune their (opto)electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p-type dopants. In an effort to control the charge transport within the bulk-heterojunction (BHJ) of OPVs, the n-type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small-molecule acceptor IT-4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n-type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge-carrier density within the BHJ, while significantly extending the cells' shelf-lifetime. The n-type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n-doping strategy highlights electron transport in NFA-based OPVs as being a key issue.