Weiss Thomas Paul, Nishiwaki Shiro, Bissig Benjamin, Buecheler Stephan, Tiwari Ayodhya N
Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
Phys Chem Chem Phys. 2017 Nov 22;19(45):30410-30417. doi: 10.1039/c7cp05236g.
Recently recorded efficiencies of Cu(In,Ga)Se based solar cells were mainly achieved by surface treatment of the absorber that modifies the buffer-absorber interface region. However, only little is known about the electronic properties within this region. In this manuscript voltage dependent admittance spectroscopy is applied to low temperature grown Cu(In,Ga)Se based solar cells to detect near interface defect states in the absorber. Under non-equilibrium conditions even defect states close to the interface may cross the Fermi level and hence are detectable using capacitance based measurement methods, in contrast to the case of zero bias conditions. Such defects are of potential importance for understanding device limitations and hence, adequate characterization is necessary. A SCAPS model is developed including a near interface deep acceptor state, which explains the frequency and voltage dependence of the capacitance. Using the same model, also the experimental apparent doping density is explained.
最近，基于Cu(In,Ga)Se的太阳能电池所记录的效率主要是通过对吸收层进行表面处理来实现的，这种处理会改变缓冲层-吸收层的界面区域。然而，对于该区域内的电子特性却知之甚少。在本论文中，电压依赖导纳谱被应用于低温生长的基于Cu(In,Ga)Se的太阳能电池，以检测吸收层中靠近界面的缺陷态。在非平衡条件下，即使是靠近界面的缺陷态也可能穿过费米能级，因此与零偏置条件的情况不同，可以使用基于电容的测量方法来检测。此类缺陷对于理解器件的局限性具有潜在的重要性，因此，进行充分的表征是必要的。开发了一个SCAPS模型，其中包括一个靠近界面的深受主态，该模型解释了电容的频率和电压依赖性。使用相同的模型，还解释了实验表观掺杂密度。
