Negligible Ion Migration in Tin‐Based and Tin‐Doped Perovskites

Abstract

Ion migration is a notorious phenomenon observed in ionic perovskite materials. It causes several severe issues in perovskite optoelectronic devices such as instability, current hysteresis, and phase segregation.Here, we report that, in contrast to lead halide perovskites (LHPs), no ion migration or phase segregation was observed in tin halide perovskites (THPs) under illumination or an electric field. The origin is attributed to a much stronger Sn-halide bond and higher ion migration activation energy (E a ) in THPs, which remain nearly constant under illumination. We further figured out the threshold E a for the absence of ion migration to be around 0.65 eV using the CsSn y Pb 1-y -(I 0.6 Br 0.4 ) 3 system whose E a varies with Sn ratios. Our work shows that ion migration does not necessarily exist in all perovskites and suggests metallic doping to be a promising way of stopping ion migration and improving the intrinsic stability of perovskites.

Compositional Design for High-Efficiency All-Inorganic Tin Halide Perovskite Solar Cells

“…The calculated phase diagram of CsSnI 3– y Br y with the obtained solution energies suggests a miscibility gap scarcely found at ambient temperature, which is substantially different from the lead analogues that show halide segregation features near ambient temperature, such as FAPbI 3– y Br y , MAPbI 3– y Br y , and CsPbI 3– y Br y . Ighodalo et al reported that tin-based and tin-doped perovskites exhibited reduced ion migration and halide segregation because of stronger Sn–halide bonds and higher ion migration activation barriers . Our ab initio thermodynamics and the report of Ighodalo alleviated our concerns regarding phase segregation in the I–Br mixture.…”

Interfacial Molecular Lock Enables Highly Efficient Tin Perovskite Solar Cells

“…Tin perovskite solar cells (TPSCs) are considered the most promising alternatives to lead perovskite solar cells (LPSCs), on account of their suitable bandgap (1.2–1.4 eV), high carrier mobility, low exciton binding energy, and long hot carrier lifetime, which enable them the potential of approaching the Shockley–Queisser limit of single-junction perovskite solar cells. − Through compositional modification and device structure optimization, the power conversion efficiency (PCE) of TPSCs has increased from 0.9 to 14.81% in the past few years. , However, the ease of Sn 2+ oxidation and halide migration frequently lead to unfavorable defect states in tin perovskites, which result in severe nonradiative recombination and fast degradation of TPSCs. − …”

Stable Tin-Based Perovskite Solar Cells

“…16 Recently, direct evidence of reduced ion migration in tin-based or tin-doped perovskite has been provided. 17 The oxidation of Sn discussed in the previous section provides a significant advantage. In Pb-based perovskite, I − is the easiest species to oxidize.…”

“…Another argument supporting the use of Sn as a strategy to stabilize the perovskite is the evidence that transistors work when employing Sn while suffering an impact to ion migration in purely Pb-based formulations . Recently, direct evidence of reduced ion migration in tin-based or tin-doped perovskite has been provided …”

“… 16 Recently, direct evidence of reduced ion migration in tin-based or tin-doped perovskite has been provided. 17 …”