Corrected Spectral Current-Matching and Physically Bounded Temperature Sensitivity in Perovskite-Silicon Tandem Solar Cells: Implications for Climate-Aware Bandgap Optimization
Year: 2026
Type: preprint
Abstract: This study numerically evaluates whether the top-cell bandgap of a two-terminal (2T) perovskite-silicon tandem solar cell that maximizes annual energy yield (EY) under realistic climatic conditions differs from the bandgap that maximizes standard-test-condition (STC) efficiency, at three climatically contrasting sites (Chittorgarh, India; Abuja, Nigeria; Leh, India). The top-cell and bottom-cell short-circuit current densities are computed by explicit numerical integration of the ASTM G173-03 (AM1.5G) reference spectrum, replacing a qualitative current-matching assumption used in an earlier version of this work; this correction shifts the STC-optimal bandgap from 1.775 eV to 1.72 eV (STC efficiency 36.11%). The temperature coefficient of the current-matching bandgap, dEg,opt/dT, is derived explicitly from this same spectral model combined with literature silicon and perovskite bandgap temperature coefficients, giving a physically bounded value of -0.32 meV/K in place of a previously unsupported assumption approximately 5.6 times larger. Under this corrected coefficient, the annual-EY-optimal bandgap converges to the same value as the STC-optimal bandgap (1.72 eV) at all three sites; a paired Monte Carlo analysis (N = 400, common draws for both designs, separating parameter-only from combined device-plus-climate uncertainty) finds no statistically supported energy-yield advantage of climate-specific bandgap selection over STC-based selection at any site (mean paired difference approximately − 0.007 kWh/m2/yr; P(delta-EY > 0) = 0.000 in every case). This withdraws this study's own previously reported climate-dependent optimization advantage. What remains robust is the gain from optimizing the top-cell bandgap toward the corrected STC optimum (1.72 eV) relative to an unoptimized 1.68 eV baseline design (6.2–6.9% annual-EY gain across the three sites); this baseline comparison should not be conflated with, and is materially different from, the (null) STC-optimal-vs-EY-optimal comparison above. The corrected model was validated at STC against a certified 2T tandem device (Voc = 1.974 V, Jsc = 20.94 mA/cm2, FF = 0.802, eta = 33.15%; Wang et al., Nature 649, 59–64, 2026), giving a normalized RMSE of 1.96%. The annual-EY, temperature-dependence, and Monte Carlo results reported here were obtained using a computational pipeline reconstructed from this manuscript's documented methodology, as the original source code was unavailable for independent verification; every reconstruction assumption is identified explicitly in the Methods and Data Availability Statement. These results demonstrate that not every intuitively plausible optimization mechanism survives rigorous physical derivation.
Source: Research Square
Author: Auwal Adam
Institution: Mewar University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204176301