Mora-Seró Ivan, Bisquert Juan, Fabregat-Santiago Francisco, Garcia-Belmonte Germà, Zoppi Guillaume, Durose Ken, Proskuryakov Yuri, Oja Ilona, Belaidi Abdelhak, Dittrich Thomas, Tena-Zaera Ramón, Katty Abou, Lévy-Clément Claude, Barrioz Vincent, Irvine Stuart J C
Departament de Ciències Experimentals, Universitat Jaume I, E-12080 Castelló, Spain.
Nano Lett. 2006 Apr;6(4):640-50. doi: 10.1021/nl052295q.
Four different types of solar cells prepared in different laboratories have been characterized by impedance spectroscopy (IS): thin-film CdS/CdTe devices, an extremely thin absorber (eta) solar cell made with microporous TiO2/In(OH)xSy/PbS/PEDOT, an eta-solar cell of nanowire ZnO/CdSe/CuSCN, and a solid-state dye-sensitized solar cell (DSSC) with Spiro-OMeTAD as the transparent hole conductor. A negative capacitance behavior has been observed in all of them at high forward bias, independent of material type (organic and inorganic), configuration, and geometry of the cells studied. The experiments suggest a universality of the underlying phenomenon giving rise to this effect in a broad range of solar cell devices. An equivalent circuit model is suggested to explain the impedance and capacitance spectra, with an inductive recombination pathway that is activated at forward bias. The deleterious effect of negative capacitance on the device performance is discussed, by comparison of the results obtained for a conventional monocrystalline Si solar cell showing the positive chemical capacitance expected in the ideal IS model of a solar cell.
不同实验室制备的四种不同类型的太阳能电池已通过阻抗谱（IS）进行了表征：薄膜CdS/CdTe器件、由微孔TiO2/In(OH)xSy/PbS/PEDOT制成的超薄吸收体（eta）太阳能电池、纳米线ZnO/CdSe/CuSCN的eta太阳能电池以及以Spiro-OMeTAD作为透明空穴导体的固态染料敏化太阳能电池（DSSC）。在所有这些电池中，在高正向偏压下均观察到了负电容行为，这与所研究电池的材料类型（有机和无机）、结构及几何形状无关。实验表明，在广泛的太阳能电池器件中，产生这种效应的潜在现象具有普遍性。提出了一个等效电路模型来解释阻抗和电容谱，其中存在一个在正向偏压下被激活的电感复合路径。通过比较传统单晶硅太阳能电池的结果，讨论了负电容对器件性能的有害影响，传统单晶硅太阳能电池在太阳能电池的理想IS模型中显示出预期的正化学电容。
