Electron Injection Efficiency and Diffusion Length in Dye-Sensitized Solar Cells Derived from Incident Photon Conversion Efficiency Measurements
Electron Injection Efficiency and Diffusion Length in Dye-Sensitized Solar Cells Derived from Incident Photon Conversion Efficiency Measurements
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DOI：
10.1021/jp809046j
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发表时间：
2009-01-22
影响因子：
3.7
通讯作者：
O'Regan, Brian C.
中科院分区：
文献类型：
--
作者：
Barnes, Piers R. F.;Anderson, Assaf Y.;O'Regan, Brian C.
染料敏化太阳能电池中的注入效率η（inj）和扩散长度L已经从电池在正面或背面照明下的光谱响应（入射光子对电流效率，IPCE）导出。从IPCE的L的值被发现是类似的2倍短于从正常的小扰动瞬态方法得到的L的值。发现IPCE导出的L（2至大于40 μ m）和η（inj）（63-90%）值与不同电池的光电流（并间接与光电压）相关，表明每个因素限制电池效率的程度。IPCE光谱随光强变化，因此从两种方法得到的扩散长度显示出相似的趋势，例如，当光强度增加10倍至约0.1太阳时，发现来自IPCE的L增加3倍，其中L趋于平稳或峰值。来自光谱响应的eta（inj）的值被证明是在定量协议与皮秒瞬态发射光谱测定。为了说明该方法的实用性，在具有和不具有TiCl（4）化学浴处理的电池上测量L和η（inj）。结果表明，TiCl（4）处理后光电流的增加是由于L增加了约2倍，尽管电子扩散系数降低了3倍。增加的L可以解释为电子复合率降低10倍。
Injection efficiency, eta(inj), and diffusion length, L, in dye-sensitized solar cells have been derived from the spectral response (incident photon to current efficiency, IPCE) of the cells under front side or backside illumination. Values of L from IPCE are found to be similar to 2 times shorter than the values of L derived from the normal small perturbation transient method. IPCE-derived values of L (2 to more than 40 mu m) and eta(inj) (63-90%) are found to correlate with the photocurrent (and indirectly with the photovoltage) of the different cells indicating the extent to which each factor limits the cell efficiency. IPCE spectra varied with light intensity, so that diffusion lengths derived from both methods show similar trends, e.g., L from IPCE is found to increase 3 times when the light intensity is increased 10 times up to approximately 0.1 sun where L tends to plateau or peak. The values for eta(inj) derived from the spectral response are shown to be in quantitative agreement with those determined from picosecond transient emission spectroscopy. To illustrate the utility of this method, L and eta(inj) were measured on cells with and without the TiCl(4) chemical bath treatment. The results show that the increase in photocurrent after the TiCl(4) treatment is due to around a 2-fold increase in L despite a 3-fold reduction in the electron diffusion coefficient. The increased L can be explained by a factor of 10 decrease in electron recombination rate.