Extremely high power conversion efficiencies (PCEs) of ≈20–22% are realized through intensive research and development of 1.5–1.6 eV bandgap perovskite absorbers. However, development of ideal bandgap (1.3–1.4 eV) absorbers is pivotal to further improve PCE of single junction perovskite solar cells (PVSCs) because of a better balance between absorption loss of sub‐bandgap photons and thermalization loss of above‐bandgap photons as demonstrated by the Shockley–Queisser detailed balanced calculation. Ideal bandgap PVSCs are currently hindered by the poor optoelectronic quality of perovskite absorbers and their PCEs have stagnated at <15%. In this work, through systematic photoluminescence and photovoltaic analysis, a new ideal bandgap (1.35 eV) absorber composition (MAPb0.5Sn0.5(I0.8Br0.2)3) is rationally designed and developed, which possesses lower nonradiative recombination states, band edge disorder, and Urbach energy coupled with a higher absorption coefficient, which yields a reduced
Here, a simple and generally applicable method of fabricating efficient and stable Pb‐Sn binary perovskite solar cells (PVSCs) based on a galvanic displacement reaction (GDR) is demonstrated. Different from the commonly used conventional approaches to form perovskite precursor solutions by mixing metal halides and organic halides such as PbI2, SnI2, MAI, FAI, etc., together, the precursor solutions are formulated by reacting pure Pb‐based perovskite precursor solutions with fine Sn metal powders. After the ratios between Pb and Sn are optimized, high PCEs of 15.85% and 18.21% can be achieved for MAPb0.4Sn0.6I3and (FAPb0.6Sn0.4I3)0.85(MAPb0.6Sn0.4Br3)0.15based PVSCs, which are the highest PCEs among all values reported to date for Pb‐Sn binary PVSCs. Moreover, the GDR perovskite‐based PVSCs exhibit significantly improved ambient and thermal stability with encapsulation, which can retain more than 90% of their initial PCEs after being stored in ambient (relative humidity (RH) ≈50%) for 1000 h or being thermal annealed at 80 °C for more than 120 h in ambient conditions. These results demonstrate the advantage of using GDR to prepare tunable bandgap binary perovskites for devices with greatly improved performance and stability.
more » « less- NSF-PAR ID:
- 10462720
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Energy Materials
- Volume:
- 9
- Issue:
- 7
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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