4‐Hydrazinobenzoic‐Acid Antioxidant for High‐Efficiency Sn–Pb Alloyed Perovskite Solar Cells

Abstract

Partial tin replacement of lead is expected to be an effective means to fine-tune the bandgap of Sn-Pb alloyed lead-halide perovskite to harvest near-infrared light and thus further increase the efficiency of solar cells based on it, in particular for use as a bottom component cell in the tandem cell design to break through the theoretical Shockley-Queisser (S-Q) limit of the single-junction solar cells. However, the efficiency of Sn-Pb alloyed perovskite solar cells (PSCs) is still lower than expected owing to the easy oxidation of Sn 2þ . Herein, a reducing agent 4-hydrazinobenzoic acid is developed as an additive to suppress the oxidation of Sn 2þ and, meanwhile, passivate surface defects. It is found that the optoelectronic performance of Sn-Pb alloyed perovskites is improved as evidenced by the mitigated trap state density and suppressed nonradiative recombination. As a result, the Sn-Pb alloyed PSC efficiency is increased to 21.09%, one of the highest for cells with this bandgap. It is expected that this method is applicable for general Sn-Pb-based perovskite optoelectronics.

Additive Engineering for Mixed Lead–Tin Narrow-Band-Gap Perovskite Solar Cells: Recent Advances and Perspectives

“…Recently, Li et al have demonstrated the use of reducing agents, such as 4-hydrazinobenzoic acid (HBA), with a hydrazine group as additives to enhance the performance of mixed Pb−Sn PSCs. 124 The introduction of the HBA additive stabilized the FA 0.5 MA 0.5 Pb 0.5 Sn 0.5 I 3 precursor solution without any color change. Fourier transform infrared (FTIR) spectra as displayed in Figure 2d indicated that the coordination bonds were formed between the amino/carboxyl groups of HBA and SnI 2 /PbI 2 in perovskite precursor solutions.…”

“…(d) FTIR spectra of HBA, PbI 2 –HBA, and SnI 2 –HBA. This panel was reproduced with permission from ref . Copyright 2022 Wiley-VCH.…”

“…(e) Photocurrent density–voltage ( J – V ) curve of the HBA-engineered Pb–Sn NBG PSCs. This panel was reproduced with permission from ref . Copyright 2022 Wiley-VCH.…”

“…Furthermore, the AA-engineered cell retained 99% of the primary PCE after 1 month of storage in the glovebox, which was much more superior to the SnF 2 -engineered device with a PCE retention rate of only 63%. Recently, Li et al have demonstrated the use of reducing agents, such as 4-hydrazinobenzoic acid (HBA), with a hydrazine group as additives to enhance the performance of mixed Pb–Sn PSCs . The introduction of the HBA additive stabilized the FA 0.5 MA 0.5 Pb 0.5 Sn 0.5 I 3 precursor solution without any color change.…”

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

“…To surmount these issues, various reductants (e.g., metallic tin, [12] hypophosphorous acid, [13] 4-hydrazinobenzoic acid, [14,15] and Hydrazine [16] ) and antioxidants (e.g., hydroxybenzene sulfonic acid, [17] gallic acid, [18] and ascorbic acid [19] ) have been introduced to restrain the oxidation reaction and retard the crystallization process, aiming to enable large grain size and a stoichiometric crystal lattice devoid of vacancies. Nevertheless, in addition to the external oxidative factor, the oxidation of Sn 2+ may be initiated by lattice instability associated with the internal defect equilibrium.…”