Designing Heterovalent Substitution with Antioxidant Attribute for High‐Performance Sn‐Pb Alloyed Perovskite Solar Cells

Abstract

All‐perovskite tandem solar cells are promising for breaking through the single‐junction Shockley–Queisser limit, and that potentially raises interest in configuring efficient Sn‐Pb alloyed narrow‐bandgap perovskite solar cells (PSCs). However, the Sn‐Pb alloyed perovskites are commonly plagued by uncontrollable crystallization dynamics and severe p‐doping levels. Herein, an effective additive molecule is designed with heterovalent substitution and antioxidant functions, whereby an organic metal coordination compound of tris(2,4‐pentanedionato)gallium (TPGa) is employed to upgrade the quality of perovskite films. Ga3+ substitution obviously boosts the formation energy of Sn vacancies and heals the trap states. Meanwhile, the crystal structure evolution process is improved by the anchoring effect of 2,4‐pentanedionato. The PSCs incorporating these improvements deliver not only a power conversion efficiency of 21.5% but also outstanding stability, as demonstrated by retaining 80% of the initial efficiency for over 1500 h. In addition, 23.14%‐efficient all‐perovskite tandem solar cells are further obtained by pairing this PSC with a wide‐bandgap (1.74 eV) top cell. This study supports the feasibility of doping trivalent ions into the Sn‐Pb alloyed perovskites to compromise the self‐p‐doping effect and highlights the importance of acetylacetone for passivating defects and hindering oxidation.

Regulating the Crystallization Growth of Sn–Pb Mixed Perovskites Using the 2D Perovskite (4-AMP)PbI4 Substrate for High-Efficiency and Stable Solar Cells

“…21 Chang et al designed an effective additive molecule, tris(2,4-pentanedionato)gallium (TPGa), in which Ga 3+ substitution significantly improved the formation energy of Sn vacancies, while the anchoring effect of 2,4pentanedionato acid improved the high crystalline quality of films. 23 Zhang et al introduced an iso-pentylammonium tetrafluoroborate ([PNA]BF 4 ) ionic salt layer as an anchoring agent to bond Pb 2+ to the surface of PEDOT:PSS to balance the crystallization rate of mixed Sn−Pb perovskites and homogeneously distribute Sn/Pb elements inside the perovskite film. 24 For the two-step preparation process, Chen et al introduced the strong coordination SCN − into the precursor solution containing PbI 2 and SnI 2 to slow the reaction rate of SnI 2 /PbI 2 with organic cations and thus not only obtained high-quality perovskite films but also retarded the oxidation of Sn 2+ during production.…”

“…Jen et al employed ascorbic acid (AA) as an additive to retard effectively the oxidation of Sn 2+ and enhance the crystal quality of the perovskite . Chang et al designed an effective additive molecule, tris­(2,4-pentanedionato)­gallium (TPGa), in which Ga 3+ substitution significantly improved the formation energy of Sn vacancies, while the anchoring effect of 2,4-pentanedionato acid improved the high crystalline quality of films . Zhang et al introduced an iso-pentylammonium tetrafluoroborate ([PNA]­BF 4 ) ionic salt layer as an anchoring agent to bond Pb 2+ to the surface of PEDOT:PSS to balance the crystallization rate of mixed Sn–Pb perovskites and homogeneously distribute Sn/Pb elements inside the perovskite film .…”

“…To regulate the crystallization rates of the Sn–Pb perovskite and suppress the oxidation of Sn 2+ in the preparation process, some strategies, such as solution engineering, additive engineering, − interface engineering, etc, had been developed. For the one-step preparation process, Zhu et al used the higher affinity dimethyl sulfoxide (DMSO) compared to DMF to form stable intermediates with metal iodides to slow down the Sn 2+ reaction rate .…”

Reductive 2D Capping Layers through Dopamine Salt Incorporation for Pb–Sn Mixed Perovskite Solar Cells

“…These defects degrade the electrical properties of perovskite films, resulting in diminished PCE. Further oxidation within the perovskite film induces PCE decay and poor stability performance. , Therefore, it is of vital importance to reduce the Sn 4+ concentration to improve the efficiency and stability of Pb–Sn mixed PSCs.…”

Reduction-Active Antisolvent: A Universal and Innovative Strategy of Further Ameliorating Additive Optimization for High Efficiency Perovskite Solar Cells

“…Organic–inorganic hybrid halide perovskite solar cells (PSCs) have attracted significant attention in recent years owing to their unique photoelectric properties, such as high absorption coefficient, efficient charge transport, long carrier diffusion, and tunable direct bandgap. − The certified power conversion efficiency (PCE) of related devices has advanced to 25.8% and is still being pushed toward the Shockley–Queisser (SQ) efficiency limit. − Although the photovoltaic performance of PSCs has developed tremendously and is now competitive with that of other commercially available solar cells, intrinsic instability remains the main obstacle that seriously limits the future applications of PSCs. Because of the soft structure and inherent ionic nature of [PbI 6 ] 4– octahedral frameworks, perovskite films are sensitive to the actual operating process and the surrounding environment, such as heat, oxygen, deformation, and humidity. − This can damage the crystal structure of the perovskite and generate undesired defects that function detrimentally as nonradiative recombination sites.…”