8.9% Single-Stack Inverted Polymer Solar Cells with Electron-Rich Polymer Nanolayer-Modified Inorganic Electron-Collecting Buffer Layers
8.9% Single-Stack Inverted Polymer Solar Cells with Electron-Rich Polymer Nanolayer-Modified Inorganic Electron-Collecting Buffer Layers
复制标题
DOI：
10.1002/aenm.201301692
复制
发表时间：
2014-05-01
影响因子：
27.8
通讯作者：
Kim, Youngkyoo
中科院分区：
文献类型：
--
作者：
Woo, Sungho;Kim, Wook Hyun;Kim, Youngkyoo
本文报道了一种富电子聚合物纳米层（聚乙烯亚胺）（PEI）放置在电子收集缓冲层（ZnO）表面后，倒置聚合物太阳能电池的功率转换效率（PCE）得到了提高。活性层由聚[[4,8-二[（2-乙基己基）氧]苯并[1,2-b:4,5-b']二噻吩-2,6-二基][3-氟-2-[（2-乙基己基）羰基]噻吩[3,4-b]噻吩二基]]（PTB7）和[6,6]-苯基- c -71-丁酸甲酯（PC71BM）的体异质结薄膜制成。通过x射线光电子能谱和光吸收测量证实，PEI纳米层的厚度被控制在2 nm，以使其绝缘效果最小。开尔文探针和紫外光电子能谱测量表明，引入PEI纳米层的PCE增强是由于ZnO层和PEI纳米层之间的界面偶极子层的形成降低了ZnO层的导带能。PEI纳米层还提高了ZnO层的表面粗糙度，从而显著降低了器件串联电阻。因此，包括短路电流密度、开路电压、填充因子和分流电阻在内的所有太阳能电池参数都得到了改善，导致PCE提高了约8.9%，接近使用共轭聚合物电解质膜的最佳PCE。
Enhanced power conversion efficiency (PCE) is reported in inverted polymer solar cells when an electron-rich polymer nanolayer (poly(ethyleneimine) (PEI)) is placed on the surface of an electron-collecting buffer layer (ZnO). The active layer is made with bulk heterojunction films of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM). The thickness of the PEI nanolayer is controlled to be 2 nm to minimize its insulating effect, which is confirmed by X-ray photoelectron spectroscopy and optical absorption measurements. The Kelvin probe and ultraviolet photoelectron spectroscopy measurements demonstrate that the enhanced PCE by introducing the PEI nanolayer is attributed to the lowered conduction band energy of the ZnO layer via the formation of an interfacial dipole layer at the interfaces between the ZnO layer and the PEI nanolayer. The PEI nanolayer also improves the surface roughness of the ZnO layer so that the device series resistance can be noticeably decreased. As a result, all solar cell parameters including short circuit current density, open circuit voltage, fill factor, and shunt resistance are improved, leading to the PCE increase up to approximate to 8.9%, which is close to the best PCE reported using conjugated polymer electrolyte films.