ACS Appl Mater Interfaces. 2009 Apr;1(4):741-5. doi: 10.1021/am800259h.
We have used ultraviolet photoelectron spectroscopy to investigate the energy-level and band alignment near the anode for poly(3-hexylthiophene)/[6,6]-phenyl-C(61)-butyric acid methyl ester (P3HT/PCBM)-based organic solar cells. Analysis of various batches of indium-tin oxide (ITO) revealed that the photoresist residues had a strong effect, reducing the work functions of ITO (Phi(ITO)) by as much as 0.61 eV. The energy-level alignment of poly(3,4-ethylenedioxythiophene)/ITO (Phi(PEDOT/ITO)) interfaces obey the Mott-Schottky rule at values of Phi(ITO) of less than 3.92 eV. In contrast, we observed Fermi-level pinning for the blend/PEDOT interfaces at values of Phi(PEDOT/ITO) greater than 4.26 eV; this finding is consistent with a previous report that the positive polaronic energy of P3HT is equal to 4.0 eV. Consequently, we suspect that the similar efficiency levels and open-circuit voltages of devices prepared from various ITO samples were due mainly to the constant interfacial energy barrier at the blend/PEDOT interface with Fermi-level pinning.
我们使用紫外光电子能谱研究了基于聚（3-己基噻吩）/[6,6]-苯基-C（61）-丁酸甲酯（P3HT/PCBM）有机太阳能电池的阳极附近的能级和能带排列。对各种批次的铟锡氧化物（ITO）的分析表明，光阻残留物有很强的影响，使 ITO 的功函数降低了 0.61eV。聚（3,4-乙二氧基噻吩）/ITO 界面的能级排列在 ITO 的 Phi(ITO)值小于 3.92eV 时符合 Mott-Schottky 规则。相比之下，我们在 Phi(PEDOT/ITO)值大于 4.26eV 时观察到了共混物/PEDOT 界面的费米能级钉扎；这一发现与之前的报告一致，即 P3HT 的正极化子能量等于 4.0eV。因此，我们怀疑，来自不同 ITO 样品的器件的相似效率水平和开路电压主要归因于共混物/PEDOT 界面的恒定界面能垒和费米能级钉扎。
