Spray-ILGAR indium sulfide buffers for Cu(In,Ga)(S,Se)2 solar cells

Nondestructive depth-resolved spectroscopic investigation of the heavily intermixed In2S3/Cu(In,Ga)Se2 interface

“…1 To replace the CdS layer by a nontoxic, more transparent buffer, and the conventionally used chemical bath deposition by a technique allowing inline processing, In 2 S 3 layers have been deposited by physical vapor deposition, 2 sputtering, 3 atomic layer deposition, 4 and spray ion layer gas reaction. 5 The In 2 S 3 /CIGSe interface has been previously investigated by different destructive depth-profiling techniques, 2,6 high-resolution transmission electron microscopy and energy dispersive x-ray analysis, 7 and x-ray photoelectron spectroscopy ͑XPS͒. 4,8,9 At ͑post-͒deposition annealing temperatures necessary for high device efficiencies ͑200-250°C͒, a pronounced diffusion of Cu and Na from the CIGSe/Mo/glass substrate into the nominal In 2 S 3 buffer layer was found in these studies.…”

Deposition of In2S3 on Cu(In,Ga)(S,Se)2 thin film solar cell absorbers by spray ion layer gas reaction: Evidence of strong interfacial diffusion

“…In 2 S 3 layers deposited by physical vapor deposition 2 ͑PVD͒, sputtering, 3 or atomic layer deposition 4,5 ͑ALD͒ are among the promising alternatives. Recently, nominal In 2 S 3 buffers were also prepared by the spray ion layer gas reaction 6 ͑Spray-ILGAR͒. The resulting CIGSSe-based solar cells yield comparable efficiencies 6 and stabilities 7 as corresponding CBD-CdS buffered references.…”

“…In the present study, the spray solution used is InCl 3 dissolved in ethanol and the reactive gas is H 2 S. A more detailed description can be found elsewhere. 6,7,14 Because of the cyclical nature of the Spray-ILGAR process, the thickness of the buffer layer can simply be adjusted by varying the number of spray cycles. A set of samples where this number has been varied between 0 ͑bare, uncovered CIGSSe absorber͒, 1, 2, 3, 4, and 6 was investigated.…”

“…The process temperature for all samples was 250°C, for which the growth rate was determined to be ϳ3.3 nm/ cycle. 6 After preparation, the ͑1/2ϫ 1 in. 2 ͒ samples were sealed in a polyethylene bag filled with N 2 .…”

“…The CIGSSe is formed by rapid thermal annealing of stacked elemental layers on Mo-coated soda-lime glass in a sulfur containing atmosphere. 13 For the preparation of the nominal In 2 S 3 layers, we used the Spray-ILGAR technique, 6,14 where a precursor solution is sprayed onto the heated absorber substrates followed by conversion of the solid film to a chalcogenide by a reactive gas. In the present study, the spray solution used is InCl 3 dissolved in ethanol and the reactive gas is H 2 S. A more detailed description can be found elsewhere.…”