Scrutinizing the Ion Migration Induced Performance Deterioration in Hole Transport Layer-Free $\text{CsSn}_{0.5}\text{Ge}_{0.5}\mathrm{I}_{3}$ Perovskite Solar Cell

Perovskite solar cells (PSC) have several potential benefits, making them a promising option for next-generation photovoltaics. Despite the efficiency gains, numerous challenges prevent this technology from being widely available. The most important one is that abnormal hysteresis in the J-V response may be caused by ion migration, which may be inherent and cannot be eliminated. This work theoretically analyzed the effects of ion migration in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{CsSn}_{\mathbf{0.5}} \mathbf{Ge}_{\mathbf{0.5}}\mathbf{I}_{\mathbf{3}}$</tex> PSC by using two defect models. The studied 1D defect models: (i) Model-1: defects at the bulk states/ defect traps, and (ii) Model-2: defects adjacent to the interface region/ interfacial defects; are simulated out in Poisson and drift-diffusion solver hosted by AC analysis (C-V, C-f (admittance), impedance) capable “SCAPS.” It is deduced from the studied models that ion migration leads to photocurrent hysteresis and can slightly but negatively impact the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{CsSn}_{\mathbf{0.5}} \mathbf{Ge}_{\mathbf{0.5}}\mathbf{I}_{\mathbf{3}}-\mathbf{based}$</tex> device performance and AC characteristics. On average, ~6.58% of efficiency is achievable for n-p structured (this work) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{CsSn}_{\mathbf{0.5}}\mathbf{Ge}_{\mathbf{0.5}}\mathbf{I}_{\mathbf{3}}$</tex> PSC, while the experimental efficiency recorded for n-i-p structure is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm \mathbf{7.11}\%$</tex>. This paper's findings are significant because they provide prediction ability to research performance deterioration pathways in noble perovskites, which is of broad interest.