Absorber Delamination-Induced Shunt Defects in Alcohol-Based Solution-Processed Cu(In,Ga)(S,Se)₂ Solar Modules

Abstract

Solution-processed chalcopyrite Cu­(In,Ga)­(S,Se)2 (CIGSSe) solar modules are promising alternatives to conventional crystalline silicon-based photovoltaic devices owing to their potential to lower production costs and compatibility with large-area flexible substrates. However, these modules typically exhibit a higher-than-expected cell-to-module loss, which, in most cases, is attributed to the emergence of critical shunt sites. In this study, we investigated the structural shunt defects induced by delamination of the absorber in alcohol-based solution-processed CIGSSe solar modules. Characterization with the use of lock-in thermography indicated that most of the delamination-induced shunt defects emerged locally near the patterned regions. Furthermore, secondary-ion mass spectroscopy measurements showed that, rather than being uniformly distributed, the alkali elements in the CIGSSe modules were concentrated near the patterned regions. The results revealed that the uniformity of this distribution is the key driving force behind absorber delamination. Finally, we confirmed that delamination-induced shunt defects can be alleviated by controlling the diffusion of alkali elements. Consequently, the energy conversion efficiency of the alcohol-based solution-processed CIGSSe solar modules was enhanced from 4.24 to 7.59% by introducing a layer that acts as a thin-film diffusion barrier.

Characterization of MOCVD-Prepared CIS Solar Cells

“…First, we compared the XRD peaks of the MOCVD-prepared CIS sample with those of the CIGS samples prepared using the other deposition techniques, i.e., the three-stage co-evaporation and two-step solution processes [6,17]. Figure 2a-c shows the three main diffraction peaks of the chalcopyrite crystals in the (112), (204/220), and (116/312) planes, respectively [18].…”

“…Finally, AZO was deposited as TCO layers via RF sputtering. The preparation of the CIGS absorber layer using the two-step solution process has been described in detail elsewhere [6].…”

“…However, the energy cost of solar cells is generally more significant than efficiency in practical applications. Solar cells can effectively replace conventional fossil fuels when their unit cost of energy is lower than or at least comparable to that of these fuels [6].…”

The Diagnosis of Shunt Defects in CIGS Modules Using Lock-In Thermography: An Empirical Comparative Study

“…We present an analysis of a CIGS mini-module by employing a system capable of both biased thermography and LIT. Through a comparison analysis, we demonstrate the efficacy of these two techniques and identify scenarios in which biased thermography performed adequately [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. We also provide an in-depth discussion of the advantages and limitations of each thermography method when diagnosing shunt defects in CIGS modules.…”

“…However, there remains a challenge in many laboratories where commercially available LIT systems are used without a comprehensive understanding of the respective strengths and drawbacks of each method. This study aimed to address this knowledge gap by conducting a comparative analysis of biased thermography and LIT, focusing on investigating shunt defects in CIGS modules [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”