Reassessing tandem photovoltaics: The case for perovskite/CIGS a multi-criteria evaluation beyond peak efficiency

Perovskite/silicon tandem solar cells currently dominate next-generation photovoltaics, driven by certified efficiencies exceeding 35% and the advantages of the established silicon manufacturing ecosystem. This efficiency-centric focus has marginalized alternative tandem architectures, particularly perovskite/Cu(In,Ga)Se₂ (perovskite/CIGS), despite their potential advantages in flexibility, lightweight deployment, radiation hardness, and environmental sustainability. Here, we argue that peak power conversion efficiency under standard test conditions is an incomplete metric for photovoltaic technology selection, because real-world applications, including utility-scale systems, building-integrated photovoltaics, aerospace platforms, and portable power, prioritize distinct combinations of performance attributes beyond efficiency alone. To address this gap, we introduce a Technology-Application Fitness (TAF) scoring framework that evaluates tandem architectures using application-specific weighting of metrics including specific power, mechanical durability, radiation tolerance, energy payback time, and levelized cost of energy, against the requirements of utility-scale terrestrial, building-integrated, space, and portable/wearable deployment scenarios. Under this framework, perovskite/CIGS tandems emerge as the highest-scoring architecture in three of four representative scenarios despite their lower headline efficiency than perovskite/silicon. We emphasize that these rankings are conditional on the proposed weighting scheme and do not represent universal technology rankings. Monte Carlo resampling of the weight vectors confirms the rankings are stable under small reweighting; under loose perturbation no rank-1 winner flipped, though the BIPV and Portable verdicts show moderate rather than strong robustness, with the Space and Utility-scale verdicts the most secure. Our analysis demonstrates that tandem photovoltaic competitiveness should be defined by deployment-specific fitness rather than peak laboratory efficiency alone. This Perspective reframes perovskite/CIGS as a strategically important platform whose application-specific value warrants greater consideration alongside efficiency-focused research priorities.