State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , 155 Yangqiao West Road, Fuzhou, Fujian 350002, P. R. China.
ACS Appl Mater Interfaces. 2013 Sep 25;5(18):9015-25. doi: 10.1021/am402175m. Epub 2013 Sep 16.
Inverted polymer solar cells (PSCs) with high open-circuit voltages of 1.00-1.06 V are fabricated by using an indenofluorene-containing copolymer (PIFTBT8) as an electron donor material and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an electron acceptor material. To improve the photovoltaic performance, interface control of various low-temperature processed ZnO films as cathode buffer layers is systematically investigated for effective electron transportation, while transition metal oxides including MoO3, WO3, NiO, and Cu2O are employed as anode buffer layers for hole-extraction. Incorporation of optimized semiconducting metal oxide interlayers can minimize interfacial power losses, which thus affords large open-circuit voltages (Voc), increased short-circuit current densities (Jsc), and fill factors (FF), eventually contributing to higher power conversion efficiencies (PCEs) as well as better device stability. Due to the improved interfacial contacts and fine-matching energy levels, inverted PSCs with a device configuration of ITO/ZnO/PIFTBT8:PC71BM/MoO3/Ag exhibit a high PCE of 5.05% with a large Voc of 1.04 V, a Jsc of 9.74 mA cm(-2), and an FF of 50.1%. For the single junction inverted PSCs with efficiencies over 5.0%, 1.04 V is the largest Voc ever achieved. By controlling the processing conditions of the active layer, the Voc can further be improved to 1.05 and 1.06 V, with PCEs of 4.70% and 4.18%, respectively. More importantly, the inverted PSCs are ascertained to maintain a PCE of 4.55% (>90% of its initial efficiency) and a Voc of 1.05 V over 180 days, demonstrating good long-term stability, which is much better than that of the conventional devices. The results suggest that the interface engineering of metal oxide interlayers is an important strategy to develop PSCs with good performance.
采用含茚并芴的共聚物（PIFTBT8）作为电子给体材料和[6,6]-苯基-C71-丁酸甲酯（PC71BM）作为电子受体材料，制备了开路电压为 1.00-1.06 V 的倒置聚合物太阳能电池（PSCs）。为了提高光伏性能，系统研究了各种低温处理的 ZnO 薄膜作为阴极缓冲层的界面控制，以有效传输电子，同时采用 MoO3、WO3、NiO 和 Cu2O 等过渡金属氧化物作为阳极缓冲层以提取空穴。掺入优化的半导体金属氧化物中间层可以最小化界面功率损耗，从而提供大的开路电压（Voc）、增加短路电流密度（Jsc）和填充因子（FF），最终提高功率转换效率（PCE）和更好的器件稳定性。由于改善了界面接触和精细匹配能级，具有 ITO/ZnO/PIFTBT8:PC71BM/MoO3/Ag 器件结构的倒置 PSCs 表现出高的 5.05%功率转换效率，Voc 为 1.04 V，Jsc 为 9.74 mA cm(-2)，FF 为 50.1%。对于效率超过 5.0%的单结倒置 PSCs，1.04 V 是迄今为止实现的最大 Voc。通过控制活性层的处理条件，Voc 可以进一步提高到 1.05 和 1.06 V，相应的 PCE 为 4.70%和 4.18%。更重要的是，倒置 PSCs 被确定在 180 天内保持 4.55%的 PCE（>其初始效率的 90%）和 1.05 V 的 Voc，表现出良好的长期稳定性，这比传统器件要好得多。结果表明，金属氧化物中间层的界面工程是开发具有良好性能的 PSCs 的重要策略。
