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This work describes the use and capabilities of Raman scattering for process monitoring and quality control applications in thin film chalcopyrite photovoltaic technologies. Main vibrational modes in the Raman spectra from the chalcopyrite layers are very sensitive to features related to their crystalline quality, chemical composition and the presence of secondary phases that are relevant for the optoelectronic properties of the absorbers and the efficiency of the solar cells and modules. Measurements performed at different process steps allow for the monitoring of the synthesis process of the chalcopyrite layers, giving information directly related to their processing conditions. These techniques have been successfully applied for the monitoring at on-line and in situ(real time) levels of the electrodeposition processes involved in the fabrication of low cost electrochemical based chalcopyrite solar cells. The results obtained corroborate the strong potential of Raman scattering for these applications, and open interesting perspectives on the development of new real time process control strategies. [ABSTRACT FROM AUTHOR]

High-performance kesterite- (CZTSe-)based solar cell devices usually employ an absorber/buffer heterostructure using toxic CdS deposited by chemical bath deposition (CBD) as a buffer layer. This is due to the favourable spike-like conduction band alignment of the CdS buffer and CZTSe absorber. ZnS(O,OH) buffer layers provide a promising nontoxic alternative. Here, variation of the thiourea concentration in the CBD of ZnS(O,OH) buffer layers and its influence on device performances of pure selenide CZTSe heterostructure solar cells is presented. Furthermore, the influence of buffer layer deposition conditions on light-induced metastabilities is discussed. A ZnS(O,OH) buffer layer deposited with a high thiourea concentration leads to distorted illuminated J–V curves as expected for devices with unfavourably high spike-like conduction band alignment between the buffer and CZTSe absorber. By adjusting the thiourea concentration J–V curve distortions can be reduced. An optimized CBD process leads to a device efficiency of up to 6.5% after light soaking, which is comparable to the efficiency of a reference device that employs CdS as the buffer layer (6.9%). [ABSTRACT FROM AUTHOR]