Tin Halide Perovskite (ASnX₃) Solar Cells: A Comprehensive Guide toward the Highest Power Conversion Efficiency

Abstract

ASnX3 perovskite solar cells (Sn‐PSC) have the potential to deliver the most efficient solar cell technology with safe materials. In this review, a comprehensive introduction of the field is given, that is suitable for nonexperts, gradually leading the reader to a narrower and detailed analysis of the most recent and significant advances. A brief description is given of the leading alternatives for lead‐free PSC and the reasons for ASnX3 compounds' status as one of the most promising candidates are presented. The last part of the review focuses on the stabilization of ASnX3, which is the most compelling challenge to achieve the highest efficiency PSCs. The most promising approaches toward stable and efficient ASnX3 PSCs are identified and discussed.

Single‐Source, Solvent‐Free, Room Temperature Deposition of Black γ‐CsSnI3 Films

“…The replacement of toxic Pb with Sn is a natural choice due to their similar ionic radius and lower toxicity of Sn. [ 2 ] The replacement of the organic cation (e.g., CH 3 NH 3 ) with Cs has been proposed to enhance the thermal stability of the material. [ 3 ] While the decomposition temperature of Cs‐based halide perovskites is higher than the ones containing organic cations, the size of the Cs + cation is at the limit for stability of the perovskite structure, and therefore causing phase instabilities [ 4–6 ] between the optically active (black) perovskite phase and the nonoptically active (yellow) nonperovskite phase.…”

Origin of Sn(ii) oxidation in tin halide perovskites

“…3 However, the efficiency of tin-based perovskite solar cells has only recently surpassed 10%, 4 mainly due to the instability of the Sn(II) oxidation state, easily oxidised to Sn(IV). 5 Although the presence of Sn(IV) in the films has been proven, it has not yet been fully explained how, and at which stage of the material and device processing, Sn(II) can be oxidised in the absence of any oxidant species, assuming that these materials are processed in inert atmospheres of shallow O 2 content (i.e. o0.1 ppm).…”

“…This fact points out that there is a limiting factor, which would be strongly influenced by the so reviewed Sn 4+ content. 5 The oxidising effect of DMSO could be behind it, therefore alternative strategies that avoid the use of this solvent have to be discovered in order to improve the performance of these devices.…”

Inorganic Pb‐Free Perovskite Light Absorbers for Efficient Perovskite Solar Cells with Enhanced Performance

“…[8] The Sn based PSCs exhibited higher short-circuit current density of 20-25 mA/cm 2 which is due to the low band gap. [9] However, the open circuit voltage is lower compared to the conventional Pb based PSCs which may be attributed to the heavy p-type doping. This p-type doping exists due to the oxidation of Sn 2 + to Sn 4 + which acted as p-type dopant in the Sn based perovskite structures.…”

“…This p-type doping exists due to the oxidation of Sn 2 + to Sn 4 + which acted as p-type dopant in the Sn based perovskite structures. [9] Further, germanium based perovskite structures which have similar optoelectronic properties to Sn/Pb based perovskites were also employed for the construction of Pb free PSCs but suffers from poor performance and fast oxidation of Ge 2 + to Ge 4 + which resulted to the worst stability under atmospheric conditions. [10,11] Bismuth (Bi) which is non-toxic in nature, high chemical stability with similar electronic configuration, ionic radii and electronegativity to Pb had been proposed by Johansson and coworkers for solar cell applications.…”