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Layered mixed tin-lead hybrid perovskite solar cells with high stability

DOI: 10.1021/acsenergylett.8b01411 DOI Help

Authors: Daniel Ramirez (Universidad de Antioquia UdeA) , Kelly Schutt (University of Oxford) , Zhiping Wang (University of Oxford) , Andrew J. Pearson (University of Cambridge) , Edoardo Ruggeri (University of Cambridge) , Henry J. Snaith (University of Oxford) , Samuel D. Stranks (University of Cambridge) , Franklin Jaramillo (Universidad de Antioquia UdeA)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Energy Letters

State: Published (Approved)
Published: August 2018
Diamond Proposal Number(s): 17223

Abstract: Tin-lead mixed metal hybrid perovskites with tunable band gaps are attractive candidates to be used as the low-band gap cell in high efficiency tandem solar cells. Nevertheless, perovskites containing tin have a greater propensity to degrade due to the fast oxidation of Sn2+ to Sn4+, which is a restrictive factor in the development of these materials. Although significant improvements are achieved with Pb:Sn mixed-metal perovskites, in comparison to neat Sn perovskites, the intrinsic instability may still pose a threat to long-term operation. For neat Pb perovskites, two dimensional (2D) hybrid perovskites, where n layers of inorganic material are separated by a long chain organic cation, generally exhibit greater stability but have lower photovoltaic performance characteristics, motivating the study of 2D/3D mixed dimension systems to realize both high efficiency and stability. In this report we demonstrate such optimal compromise between performance and stability using formamidinium, cesium and t-butylammonium as A-site cations with Pb:Sn mixed metal low band gap perovskites. As determined by film structure measurements, the optimised 2D perovskite phases facilitate improved luminescence efficiency, which we infer to be via surface defect site passivation. Perovskite solar cells based on n = 4 and n = 5 lead-tin perovskites achieved power conversion efficiencies of up to 9.3% and 10.6%, respectively and correspondingly retained 47% and 29% of their initial efficiency during storage in nitrogen for 2000 hours. A similar stability trend for n = 4 over n = 5 was also observed for unencapsulated devices during continuous operation under combined air atmosphere and temperature for 10 hours, resulting in improved stability over the 3D lead-tin counterpart.

Diamond Keywords: Photovoltaics; Semiconductors

Subject Areas: Materials, Chemistry, Energy

Instruments: I07-Surface & interface diffraction

Added On: 28/08/2018 08:25

Discipline Tags:

Surfaces Earth Sciences & Environment Sustainable Energy Systems Energy Physics Climate Change Chemistry Materials Science interfaces and thin films Inorganic Chemistry Perovskites Metallurgy

Technical Tags:

Scattering Wide Angle X-ray Scattering (WAXS) Grazing Incidence Wide Angle Scattering (GIWAXS)