CIGS precursor films

Figure 7.6. SEM of the electrodeposited CIGS precursor film (a) surface morphology and (b) cross section. 

The electroless process for preparing CIGS precursor films is accomplished by the combination of electrochemical and chemical reactions. The counter-electrode (Fe) initiates the electrochemical reaction. The electroless deposition of CIGS is most likely caused as follows ... 

Nonvacuum electrodeposition and electroless deposition techniques have the potential to prepare large-area uniform precursor films using low-cost source materials and low-cost capital equipment. Therefore, these techniques are very attractive for growing CIGS layers for photovoltaic applications. 

Figure 3 shows X-ray diffraction data of the absorber CIGS film prepared from ED and EL precursor films after compositional adjustment. The as-deposited films were amorphous or polycrystalline in nature. The absorber film after final film composition adjustment shows only the CIGS phase. The International Center for Diffraction Data card number used for the identification of CIGS X-ray peaks is 40-1487. ... 

The ED and EL deposition processes are simple and fast, and they can synthesize binary or multinary precursors for subsequent processing into high-quality CIGS thin-film absorbers for solar cells. The device fabricated using ED precursor layers resulted in efficiencies as high as 15.4%. The quality of CIGS-based films and devices prepared from ED precursors is very promising. This may lead to novel, fast, and low-cost methods for solar-cell absorber fabrication. 

Deposition of CIGSSe absorber layers by electro-spraying a propylene glycol solution of copper(ii), In(m) and Ga(iii) nitrates as metal precursors has been reported. The ratio of the metal nitrates was adjusted to yield 1 0.7 0.3 ratio of Cu, In and Ga, respectively in final films. The thin films thus obtained were annealed in air at 300 °C for minutes, sulfurized in dilute HjS stream (1% in N2) at 500 °C for 30 minutes and finally selenized at 500 °C for 10 minutes. Characterization of the films by p-XRD and SEM (Fig. 26) studies revealed that polycrystalline CIGS nanostructures are formed as a result of this post treatment. 

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