Fabrication of CIGS thin film absorber by laser treatment of pre-deposited nano-ink precursor layer

Abstract

A process to prepare Copper Indium Gallium Selenide (CIGS) absorber thin films by laser treatment of pre-deposited nano-inks has been investigated. Two approaches were followed, one using an ink of CIGS nanoparticles and other employing an ink comprising a mixture of a CIG metallic alloy and Se nanoparticles. Laser post treatment of the film applied with the CIGS ink was found to retain the chalcopyrite structure following melting and recrystallization, with no additional phases being generated during the process. Single-phase, highly crystalline CIGS thin films were also found to result from the ink made of CuIn 0.7 Ga 0.3 and Se nanoparticles precursor following laser treatment. The CuIn 0.7 Ga 0.3 Se 2 thin films obtained in both cases were consistent with the initial constitution of the precursor materials used in terms of the Ga/(Ga+In) ratio. The prepared films were comprehensively characterized using XRD, SEM-EDS and XRF. Results reveal that the above non-vacuum approach obviating the need for a selenization step is simple, quick and expected to have a large impact on the overall process economics for fabrication of CIGS thin film solar cells.

Crystalline Engineering Toward Large-Scale High-Efficiency Printable Cu(In,Ga)Se2 Thin Film Solar Cells on Flexible Substrate by Femtosecond Laser Annealing Process

“…Thus, the process has been ubiquitously employed in small-area dopant-activation of semiconductors currently to replace the more conventional annealing methods, including furnace annealing (FA) and rapid thermal annealing (RTA). − In addition, laser crystallization has been implemented in solar cell production for attaining higher device performances than conventional thermal annealing . Previous studies, using continuous-wave (CW) and ns-pulsed lasers, have indicated that LA treatment indeed is a viable approach for improving the crystallinity and mobility of CIGS thin films obtained by different processes. − However, these laser sources turn out to be inappropriate for the LA treatment process applied to CIGS thin films from the current nonvacuum synthesis because these nonvacuum CIGS films are very sensitive to residual heat . On the other hand, the fs-laser has been recognized as a novel tool for annealing amorphous silicon without inducing the heating effect to vicinity regions .…”

Parametric optimization of mechanochemical process for synthesis of Cu(In, Ga)0.5Se2 nanoparticles

“…Non-vacuum techniques are broadly classified into molecular precursor approach including electrodeposition, spray pyrolysis and nanoparticle approach [9]. Nanoparticle approach involves synthesis and deposition of nanoparticle based precursor material onto a substrate using cost effective simple methods such as spin coating [10], spraying [11], screen printing [12] and doctor blade [13]. Nanoparticle approach is regarded as a feasible method due to good control over atomic concentrations [13], high material usage and simplicity in scale up [3].…”

A facile route for synthesis of CuInxGa1−xSe2 nanocrystals with tunable composition for photovoltaic application

“…And the world record for thin-film solar performance is back in the hands of researchers at Stuttgart's Centre for Solar Energy and Hydrogen Research (ZSW) after scientists achieved a 21.7 % efficiency with a new CIGS solar cell. Nevertheless, considering the high cost of vacuum methods such as co-evaporation [3,5] and sputtering [6], the non-vacuum methods such as solution-based nanoparticle ink [7][8][9] may lead to an inexpensive fabrication route for CIGS lightabsorbing layers [10,11]. However, it is challenging to develop a facile route to prepare CIGS nanocrystals which can be readily formed into a CIGS absorbing layer for thinfilm solar cells.…”