State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China.
Phys Chem Chem Phys. 2014 Mar 14;16(10):4528-37. doi: 10.1039/c3cp55075c.
In this work, solvent chloronaphthalene (CN) and polymer acceptor an alternating copolymer of perylene diimide and carbazole (PCPDI) were utilized as co-additives to optimize the nanoscale phase-separated morphology and photovoltaic properties of bulk-heterojunction (BHJ) polymer solar cells based on the poly(3-hexyl thiophene) (P3HT)/N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (EP-PDI) system. The domain size of EP-PDI molecules together with that of P3HT distinctly decreased by adding a 0.75 vol% CN additive. The optimized lateral phase separation increased the donor-acceptor interfacial area and facilitated the exciton dissociation process, leading to 5-fold enhancement of short-circuit current (JSC). Furthermore, when PCPDI was employed as a co-additive, acceptor materials (including PCPDI and EP-PDI) were prone to aggregation towards the top surface of blend films, improving vertical phase separation of active layers. PCPDI incorporation, which improved the percolation pathways for electron carriers, suppressed the crystallinity of P3HT distinctly. Thus, much more balanced charge transport was achieved by PCPDI addition, which resulted in almost 1-fold enhancement of open-circuit voltage (VOC) by reducing nongeminate recombination. As a consequence, cooperative effects of CN and PCPDI additives improved the nanoscale phase-separated morphology in lateral and vertical directions simultaneously, achieving the enhancement in both VOC and JSC.
在这项工作中，溶剂氯萘（CN）和聚合物受体苝二酰亚胺和咔唑的交替共聚物（PCPDI）被用作共添加剂，以优化基于聚（3-己基噻吩）（P3HT）/N，N'-双（1-乙基丙基）-苝-3,4,9,10-四羧酸二酰亚胺（EP-PDI）体系的体异质结（BHJ）聚合物太阳能电池的纳米级相分离形态和光伏性能。通过添加 0.75 体积%的 CN 添加剂，EP-PDI 分子的畴尺寸以及 P3HT 的畴尺寸明显减小。优化的横向相分离增加了给体-受体界面面积并促进了激子解离过程，导致短路电流（JSC）增加了 5 倍。此外，当 PCPDI 用作共添加剂时，受体材料（包括 PCPDI 和 EP-PDI）容易在共混膜的顶部表面聚集，改善了活性层的垂直相分离。PCPDI 的掺入改善了电子载流子的渗流途径，明显抑制了 P3HT 的结晶度。因此，PCPDI 的加入实现了更平衡的电荷输运，通过减少非辐射复合，开路电压（VOC）几乎提高了 1 倍。结果，CN 和 PCPDI 添加剂的协同效应同时改善了横向和垂直方向的纳米级相分离形态，从而提高了 VOC 和 JSC。
