Department of Polymer Engineering, College of Polymer Science and Polymer Engineering, The University of Akron , Akron, Ohio 44325, United States.
State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, P. R. China.
ACS Appl Mater Interfaces. 2017 Feb 15;9(6):5348-5357. doi: 10.1021/acsami.6b13642. Epub 2017 Feb 6.
In this paper, we report the highly efficient bulk heterojunction (BHJ) polymer solar cells (PSCs) with an inverted device structure via utilizing an ultrathin layer of lithium sulfonated polystyrene (LiSPS) ionomer to reengineer the surface of the solution-processed zinc oxide (ZnO) electron extraction layer (EEL). The unique lithium-ionic conductive LiSPS contributes to enhanced electrical conductivity of the ZnO/LiSPS EEL, which not only facilitates charge extraction from the BHJ active layer but also minimizes the energy loss within the charge transport processes. In addition, the organic-inorganic LiSPS ionomer well circumvents the coherence issue of the organic BHJ photoactive layer on the ZnO EEL. Consequently, the enhanced charge transport and the lowered internal resistance between the BHJ photoactive layer and the ZnO/LiSPS EEL give rise to a dramatically reduced dark saturation current density and significantly minimized charge carrier recombination. As a result, the inverted BHJ PSCs with the ZnO/LiSPS EEL exhibit an approximatively 25% increase in power conversion efficiency. These results indicate our strategy provides an easy, but effective, approach to reach high performance inverted PSCs.
在本文中，我们报告了通过利用超薄的磺化聚苯乙烯锂（LiSPS）离聚物来重新设计溶液处理的氧化锌（ZnO）电子萃取层（EEL）的表面，实现高效的体异质结（BHJ）聚合物太阳能电池（PSCs）的具有倒置器件结构。独特的锂离子导电 LiSPS 有助于提高 ZnO/LiSPS EEL 的电导率，这不仅有助于从 BHJ 活性层中提取电荷，还最大限度地减少了电荷输运过程中的能量损失。此外，有机-无机 LiSPS 离聚物很好地解决了 BHJ 光活性层在 ZnO EEL 上的相干问题。因此，增强的电荷输运和 BHJ 光活性层与 ZnO/LiSPS EEL 之间降低的内阻导致暗饱和电流密度显著降低，电荷载流子复合显著减少。结果，具有 ZnO/LiSPS EEL 的倒置 BHJ PSCs 的功率转换效率提高了约 25%。这些结果表明，我们的策略为实现高性能倒置 PSCs 提供了一种简单而有效的方法。
