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

Abstract

Low-cost perovskite solar cells (PSCs) with high power conversion efficiencies (PCEs) of >25% are considered as the most promising replacement for commercial silicon-based solar cells to realize a sustainable future. To break the theoretical PCE limits of single-junction PSCs, all-perovskite tandem solar cells consisting of a narrow-band-gap bottom subcell and a wide-band-gap top subcell have attracted particular attention recently. Mixed Pb–Sn perovskites with narrow band gaps have received great attention as an efficient light harvester in the bottom subcell of all-perovskite tandem solar cells as a result of the reduced toxicity, high light-absorbing capability, and matched current with the wide-band-gap top subcells. However, mixed Pb–Sn narrow-band-gap PSCs suffer from low PCEs, inferior stability, and high open-circuit voltage (V oc) loss, owing to the high defect amount and inferior perovskite film quality induced by the detrimental oxidation of Sn2+ cations and the rapid crystallization of perovskite crystals. Herein, the recent advances about the additive engineering for mixed Pb–Sn narrow-band-gap PSCs are reviewed by demonstrating the origins and unique features of Pb–Sn narrow-band-gap perovskites. Additionally, several strategies to improve PCEs and durability of Pb–Sn narrow-band-gap PSCs through additive engineering are proposed, including Sn2+ cation stabilization, heterojunction construction, crystallization control, surface/grain boundary passivation, film morphology control, carrier dynamics modulation, and gradient-distributed film formation. Furthermore, the existing challenges and future directions are also presented, aiming to provide important insights for designing and developing efficient and stable single-junction narrow-band-gap PSCs and all-perovskite tandem solar cells.

Perovskite Quantum Dot Solar Cells: Current Status and Future Outlook

“…Figure f depicts theoretical PCEs based on the bandgap and MEG thresholds of the material and the reported MEG efficiencies of PQDs with different compositions . Small bandgap perovskite materials, including Sn-based or Pb–Sn-based PQDs and FPI QDs, can be promising candidates to achieve efficiencies over the SQ limit by unlocking the potential of MEG, especially for Sn-based or Pb–Sn alloyed QDs that possess a bandgap of ∼1.2 eV, enhanced MEG efficiency, reduced threshold energy, and prolonged multiexciton lifetime (Figure f). , For CsPbBr 3 and CPI QDs that have large bandgaps, they are more suitable for high-energy photon detection or solar cells used in space by efficiently harvesting high-energy photons. From the device design point of view, the built-in electric field can be further enhanced to facilitate the collection of multiexcitons, which can be achieved by the construction of a homojunction structure with a castigated energy band alignment or p–n junctions.…”

Templated-seeding renders tailored crystallization in perovskite photovoltaics: path towards future efficient modules

“…81 Additionally, uniformity, determined by film coverage and surface potential, plays a crucial role in the fill factor and open-circuit voltage of the device. 26 Seed-assisted crystallization technology is effective in inducing grain growth, enhancing crystallization quality, and expanding coverage. Utilizing seed-assisted growth in the perovskite crystallization process offers a promising approach to enhance template-guided crystallization, reduce reliance on anti-solvent methods, and eliminate the need for volatile perovskite precursors.…”

“…However, the efficiency improvements achieved to date in PSCs have been constrained to small areas; scaling these advances to larger areas remains a significant challenge. 26…”

Review on Functional Electrolyte, Redox Polymers, and Solar Conversions in 3G Emerging Photovoltaic Technologies: Progress and Outlook

“…Perovskite materials have long electron diffusion lengths and high absorption characteristic structures. − Recently, low cost perovskite solar cells are viewed as the next generation solar conversion (PCE >25%) system, which is an alternative of Si-based solar cells. , Focusing on the stability issue, using nonionic Au-NPs as dopants should be able to avoid the penetration of water molecules though P3HT. Dopants are incorporated to the hole transport structure to improve hole mobility.…”