School of Integrative Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-gu, Seoul 156-756 (Republic of Korea).
ChemSusChem. 2015 Jan;8(2):331-6. doi: 10.1002/cssc.201402833. Epub 2014 Nov 17.
We demonstrate that reproducible results can be obtained from tandem solar cells based on the wide-bandgap poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and the diketopyrrolopyrrole (DPP)-based narrow bandgap polymer (DT-PDPP2T-TT) with a decyltetradecyl (DT) and an electron-rich 2,5-di-2-thienylthieno[3,2-b]thiophene (2T-TT) group fabricated using an optimized interlayer (ZnO NPs/ph-n-PEDOT:PSS) [NPs: nanoparticles; ph-n: pH-neutral PEDOT: poly(3,4-ethylenedioxythiophene); PSS: polystyrene sulfonate]. The tandem cells are fabricated by applying a simple process without thermal annealing. The ZnO NP interlayer operates well when the ZnO NPs are dispersed in 2-methoxyethanol, as no precipitation and chemical reactions occur. In addition to the ZnO NP film, we used neutral PEDOT:PSS as a second interlayer which is not affect to the sequential deposited bulk heterojunction (BHJ) active layer of acidification. The power conversion efficiency (PCE) of a tandem device reaches 7.4 % (open-circuit voltage VOC =1.53 V, short-circuit current density JSC =7.3 mA cm(-2) , and fill factor FF=67 %). Furthermore, FF is increased to up to 71 % when another promising large bandgap (bandgap ∼1.94 eV) polymer (PBnDT-FTAZ) is used. The surface of each layer with nanoscale morphology (BHJ1/ZnO NPs film/ph-n-PEDOT:PSS/BHJ2) was examined by means of AFM analysis during sequential processing. The combination of these factors, efficient DPP-based narrow bandgap material and optimized interlayer, leads to the high FF (average approaches 70 %) and reproducibly operating tandem BHJ solar cells.
我们证明，基于宽带隙聚[N-9'-十七烷基-2,7-咔唑-alt-5,5-(4,7-二-2-噻吩基-2',1',3'-苯并噻二唑)]（PCDTBT）和基于二酮吡咯并吡咯（DPP）的窄带隙聚合物（DT-PDPP2T-TT）的串联太阳能电池可以获得可重复的结果，这些电池使用优化的层（ZnO NPs/ph-n-PEDOT：PSS）[NPs：纳米颗粒；ph-n：pH 中性 PEDOT：聚（3,4-乙二氧基噻吩）；PSS：聚苯乙烯磺酸盐]来制造，其中包含癸基十四烷基（DT）和富电子 2,5-二-2-噻吩基噻吩[3,2-b]噻吩（2T-TT）基团。这些串联电池是通过不进行热退火的简单工艺制造的。当 ZnO NPs 分散在 2-甲氧基乙醇中时，ZnO NP 层表现良好，因为不会发生沉淀和化学反应。除了 ZnO NP 薄膜之外，我们还使用中性 PEDOT：PSS 作为第二层，它不会影响酸化的顺序沉积的本体异质结（BHJ）活性层。串联器件的功率转换效率（PCE）达到 7.4％（开路电压 VOC =1.53 V，短路电流密度 JSC =7.3 mA cm（-2），填充因子 FF =67％）。此外，当使用另一种有前途的大带隙（带隙≈1.94 eV）聚合物（PBnDT-FTAZ）时，FF 增加到高达 71％。通过在顺序处理过程中对各层的纳米级形貌（BHJ1/ZnO NPs 薄膜/ph-n-PEDOT：PSS/BHJ2）进行 AFM 分析，对各层的纳米级形貌进行了检查。这些因素的结合，即高效的基于 DPP 的窄带隙材料和优化的层，导致高 FF（平均值接近 70％）和可重复操作的串联 BHJ 太阳能电池。
