Enhancing Next-Gen Photovoltaic Cells: Unveiling Optoelectronic Properties through Hyperspectral Imaging

In recent years, the photovoltaics scene has undergone significant transformations, resulting in an unprecedented diversity of solar materials. Despite recent advancements, the widespread commercialization of most emerging technologies remains challenging. This can be partly attributed to material inhomogeneities and the difficulties associated with up-scaling. One specific aspect that requires attention to bridge the cell-to-module gap while maintaining high efficiencies in both CIGS and perovskite-based solar cells, is the laser patterning process for series interconnections of cells. It is crucial to establish control over the underlying process of P1, P2, and P3 laser ablation lines and identify any associated power losses. <br/> <br/>The optimization of a solar cell fabrication process, including the laser ablation process, requires high-performance and specialized measurement systems. To address this demand, Photon etc, in collaboration with IRDEP (Institute of Research and Development on Photovoltaic Energy), has developed a global hyperspectral imaging platform (IMA™) for solar cell analysis. This platform provides rapid acquisition of photoluminescence (PL), electroluminescence (EL), and absorbance maps. Most luminescence imaging characterization techniques provide data in arbitrary units, which limits their interpretation because of the lack of information. With this challenge in mind, researchers at IRDEP have designed a method for spectral and photometric calibration [1]. This technique has been implemented in Photon etc.’s platform and allows obtaining the absolute number of photons emitted at a specific energy from every point on the sample's surface. By performing this calibration, researchers can further investigate Planck’s law to access the quasi-fermi level splitting (QFLS) [2]. <br/> <br/>In this framework, we combined global hyperspectral imaging with absolute calibrated photoluminescence to extract spatial distribution of several optoelectronic of triple cation perovskite (Cs_0.05(FA_0.79MA_0.16)_0.95PbI_2.49Br_0.0,51), CIGS (Cu(In_x,Ga_1x)Se₂) [3] and CIGS/perovskite tandem solar cells patterned with ns and ps laser pulses. Maps of the PL quantum yield (PLQY), effective QFLS, open circuit voltage (V_oc), Urbach energy (E_u), optical diode factor (ODF), and shunt resistance (R_sh) were obtained. These mappings provide insights that help determine the optimum process window for patterning. Moreover, this hyperspectral imaging system enables selective excitation and characterization of the bottom cell (CIGS) and the top cell (perovskite). This capability allows a spatially resolved detection and analysis of the laser-induced defects at each individual patterning step, thereby enabling conclusions to be drawn regarding the specific effects on each sub-cell.<br/> <br/>[1] Delamarre, A., Paire, M., Guillemoles, J.-F., & Lombez, L. (2014). Quantitative luminescence mapping of Cu(In, Ga)Se2thin-film solar cells. In Progress in Photovoltaics: Research and Applications (Vol. 23, Issue 10, pp. 1305–1312). Wiley. https://doi.org/10.1002/pip.2555<br/>[2] Rau, U. (2007). Reciprocity relation between photovoltaic quantum efficiency and electroluminescent emission of solar cells. In Physical Review B (Vol. 76, Issue 8). American Physical Society (APS). https://doi.org/10.1103/physrevb.76.085303<br/>[3] Ramírez Quiroz, C. O., Dion-Bertrand, L.-I., Brabec, C. J., Müller, J., & Orgassa, K. (2020). Deciphering the Origins of P1-Induced Power Losses in Cu(In Ga1–)Se2 (CIGS) Modules Through Hyperspectral Luminescence. In Engineering (Vol. 6, Issue 12, pp. 1395–1402). Elsevier BV. https://doi.org/10.1016/j.eng.2019.12.019