Perovskite–silicon tandem solar cells (TSCs), due to their complementary bandgap alignment and low-cost fabrication potential, can surpass the efficiency limits of single-junction solar cells. The present work focuses on the design and optimization of a two-terminal (2T) CsSnBr₃/Si tandem architecture and investigates how voltage, recombination, and resistive losses govern tandem-device performance. A combined detailed-balance and SCAPS-1D framework is developed to compare ideal, realistic, and degraded device conditions. The detailed-balance analysis shows that non-radiative recombination in the perovskite absorber significantly reduces the open-circuit voltage and overall efficiency compared to the ideal radiative limit. The ideal detailed-balance case predicts an efficiency of approximately 46% (Shockley–Queisser limit) with an optimum top-cell bandgap range of 1.70–1.75 eV. When a voltage loss of 0.30–0.50 eV per sub-cell is introduced, the theoretical tandem efficiency decreases from approximately 36% to 29%, indicating the strong influence of recombination losses on tandem performance. The SCAPS simulations follow a similar trend. Under ideal conditions, the tandem device achieves a power conversion efficiency of 36.15% with <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{V}_{oc}=1.85\)</EquationSource> </InlineEquation>V, <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:{J}_{sc}=23.40\)</EquationSource> </InlineEquation>mA cm−2, and FF = 83.50%. Under realistic conditions, including moderate bulk/interface defect densities and resistive losses, the efficiency decreases to 28.97% with <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\:{V}_{oc}=1.77\)</EquationSource> </InlineEquation>V, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\:{J}_{sc}=21.40\)</EquationSource> </InlineEquation>mA cm− 2, and FF = 76.50%. A degraded case incorporating high bulk defect density (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\:{10}^{15}\)</EquationSource> </InlineEquation> cm−3), elevated interface defect densities (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\:{10}^{12}\)</EquationSource> </InlineEquation> cm−2), series resistance (<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\:4\:{\Omega\:}\:{\text{cm}}^{2}\)</EquationSource> </InlineEquation>), and low shunt resistance (<InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\:200\:{\Omega\:}\:{\text{cm}}^{2}\)</EquationSource> </InlineEquation>) reduces the efficiency to 19.55% with <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\:{V}_{oc}=1.72\)</EquationSource> </InlineEquation>V, <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\:{J}_{sc}=19.92\)</EquationSource> </InlineEquation>mA cm− 2, and FF = 57.09%. The results demonstrate that the transition from detailed-balance limits to experimentally relevant performance is governed not only by defect-assisted recombination, but also by interface and resistive losses that strongly suppress voltage and fill factor. Compared with the ideal device, the degraded tandem shows only a moderate reduction in <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\:{J}_{sc}\:\)</EquationSource> </InlineEquation>and <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(\:{V}_{oc}\)</EquationSource> </InlineEquation>, while the largest performance loss occurs in the fill factor, indicating that recombination and resistive transport losses mainly affect carrier extraction rather than light absorption. The study further highlights the gap between idealized simulation limits and practical device conditions, while identifying the material and device parameters required to achieve high-efficiency lead-free perovskite–silicon TSC.

Modeling of a two-terminal perovskite–silicon tandem solar cell using lead-free inorganic PSC: ideal and realistic performance limits

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发表日期：

2026年7月20日

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Sidra Khatoon,
Satish Kumar Yadav,
Jyotsna Singh,
Rajendra Bahadur Singh,
S. M. Mozammil Hasnain

摘要

Perovskite–silicon tandem solar cells (TSCs), due to their complementary bandgap alignment and low-cost fabrication potential, can surpass the efficiency limits of single-junction solar cells. The present work focuses on the design and optimization of a two-terminal (2T) CsSnBr₃/Si tandem architecture and investigates how voltage, recombination, and resistive losses govern tandem-device performance. A combined detailed-balance and SCAPS-1D framework is developed to compare ideal, realistic, and degraded device conditions. The detailed-balance analysis shows that non-radiative recombination in the perovskite absorber significantly reduces the open-circuit voltage and overall efficiency compared to the ideal radiative limit. The ideal detailed-balance case predicts an efficiency of approximately 46% (Shockley–Queisser limit) with an optimum top-cell bandgap range of 1.70–1.75 eV. When a voltage loss of 0.30–0.50 eV per sub-cell is introduced, the theoretical tandem efficiency decreases from approximately 36% to 29%, indicating the strong influence of recombination losses on tandem performance. The SCAPS simulations follow a similar trend. Under ideal conditions, the tandem device achieves a power conversion efficiency of 36.15% with \(\:{V}_{oc}=1.85\) V, \(\:{J}_{sc}=23.40\) mA cm⁻², and FF = 83.50%. Under realistic conditions, including moderate bulk/interface defect densities and resistive losses, the efficiency decreases to 28.97% with \(\:{V}_{oc}=1.77\) V, \(\:{J}_{sc}=21.40\) mA cm^− 2, and FF = 76.50%. A degraded case incorporating high bulk defect density ( \(\:{10}^{15}\) cm⁻³), elevated interface defect densities ( \(\:{10}^{12}\) cm⁻²), series resistance ( \(\:4\:{\Omega\:}\:{\text{cm}}^{2}\) ), and low shunt resistance ( \(\:200\:{\Omega\:}\:{\text{cm}}^{2}\) ) reduces the efficiency to 19.55% with \(\:{V}_{oc}=1.72\) V, \(\:{J}_{sc}=19.92\) mA cm^− 2, and FF = 57.09%. The results demonstrate that the transition from detailed-balance limits to experimentally relevant performance is governed not only by defect-assisted recombination, but also by interface and resistive losses that strongly suppress voltage and fill factor. Compared with the ideal device, the degraded tandem shows only a moderate reduction in \(\:{J}_{sc}\:\) and \(\:{V}_{oc}\) , while the largest performance loss occurs in the fill factor, indicating that recombination and resistive transport losses mainly affect carrier extraction rather than light absorption. The study further highlights the gap between idealized simulation limits and practical device conditions, while identifying the material and device parameters required to achieve high-efficiency lead-free perovskite–silicon TSC.