From theory to practice: Reassessing the Shockley–Queisser limit for next-generation solar cells

With the power conversion efficiency of crystalline silicon solar cells approaching the theoretical limit of 29.4% and the efficiency of perovskite/silicon tandem solar cells exceeding 35%, a precise understanding of the physical connotations of the Shockley–Queisser (S–Q) limit and its future breakthrough pathways is critical for the selection of next-generation photovoltaic technology routes. This paper systematically reviews this classic theory and conducts a comparative analysis of several mathematical approximations and fitting results involved in the theory. A quantitative relationship between the open-circuit voltage (VOC) and the bandgap voltage (Vg) under different solar spectra is derived, which can be used for the rapid engineering assessment of VOC losses in solar cells. The relationship between the experimentally achieved key parameters and the theoretical limits of several typical solar cells is compared and discussed. The S–Q theory is further employed to systematically analyze the VOC loss in perovskite solar cells. Finally, pathways to transcend the S–Q limit are briefly discussed.