Fabrication of Efficient Low-Bandgap Perovskite Solar Cells by Combining Formamidinium Tin Iodide with Methylammonium Lead Iodide

Abstract

Mixed tin (Sn)-lead (Pb) perovskites with high Sn content exhibit low bandgaps suitable for fabricating the bottom cell of perovskite-based tandem solar cells. In this work, we report on the fabrication of efficient mixed Sn-Pb perovskite solar cells using precursors combining formamidinium tin iodide (FASnI3) and methylammonium lead iodide (MAPbI3). The best-performing cell fabricated using a (FASnI3)0.6(MAPbI3)0.4 absorber with an absorption edge of ∼1.2 eV achieved a power conversion efficiency (PCE) of 15.08 (15.00)% with an open-circuit voltage of 0.795 (0.799) V, a short-circuit current density of 26.86(26.82) mA/cm(2), and a fill factor of 70.6(70.0)% when measured under forward (reverse) voltage scan. The average PCE of 50 cells we have fabricated is 14.39 ± 0.33%, indicating good reproducibility.

Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

“…The mixing of the monovalent cations is one of the most commonly employed methods in the composition engineering of Pb‐based perovskites22, 23, 24 and Pb/Sn‐based binary perovskites,25, 26, 27 which combines the merits of perovskites with different cations. To the best of our knowledge, there has been no report by now on the composition engineering of purely Sn‐based perovskites.…”

Lead‐Free Hybrid Perovskite Absorbers for Viable Application: Can We Eat the Cake and Have It too?

“…They are the most studied hybrid halide perovskites with the formula APb l M 1−l X 3 (A = CH 3 NH 3 , HC(NH 2 ) 2 , Cs, Rb, or their mixture; M = Sn (II),5, 6, 7, 8 Ge (II),9, 10 Mn (II),11 Co (II),12 In (III),13 Al (III),14 or Sb (III),15 etc. or their mixture; X = Cl, Br, I, or their mixture) featuring the containing of Pb as the main metal cation and 3D network of corner‐sharing (Pb 1−l M l )X 6 4− octahedrons with the monovalent cation occupying the cuboctahedral cavity.…”

Optical response of mixed methylammonium lead iodide and formamidinium tin iodide perovskite thin films

“…Literature reports several ways of making low band gap perovskite materials: substituting Pb by Sn in MAPbI 3 , 2 substituting methylamine (MA) by formylamine (FA) and Pb by Sn in MAPbI 3 3 and combining a formamidinium tin iodide (FASnI 3 ) precursor with a MAPbI 3 precursor. 4 Among those, combining a FASnI 3 precursor with a MAPbI 3 precursor makes a high-quality (FASnI 3 ) 1-x (MAPbI 3 ) x film and has produced a 15% efficient solar cell, which is the highest efficiency for a low band gap long wavelength light absorbing Sn-Pb based perovskite solar cells to date. 1,4 For the MASn 1-x Pb x I 3 system Mosconi et al 5 (2014) has theoretically calculated the absorption coefficient (α) and Anaya et al 2 has reported experimental complex optical properties of MASn 1-x Pb x I 3 films.…”

“…4 Among those, combining a FASnI 3 precursor with a MAPbI 3 precursor makes a high-quality (FASnI 3 ) 1-x (MAPbI 3 ) x film and has produced a 15% efficient solar cell, which is the highest efficiency for a low band gap long wavelength light absorbing Sn-Pb based perovskite solar cells to date. 1,4 For the MASn 1-x Pb x I 3 system Mosconi et al 5 (2014) has theoretically calculated the absorption coefficient (α) and Anaya et al 2 has reported experimental complex optical properties of MASn 1-x Pb x I 3 films. The optical properties of (FASnI 3 ) 1-x (MAPbI 3 ) x are reported by Liao et al 4 where the spectral range is limited to the absorption band edge energy region with numerical interpolation and extrapolation-based B-spline parameterizations applied.…”

“…1,4 For the MASn 1-x Pb x I 3 system Mosconi et al 5 (2014) has theoretically calculated the absorption coefficient (α) and Anaya et al 2 has reported experimental complex optical properties of MASn 1-x Pb x I 3 films. The optical properties of (FASnI 3 ) 1-x (MAPbI 3 ) x are reported by Liao et al 4 where the spectral range is limited to the absorption band edge energy region with numerical interpolation and extrapolation-based B-spline parameterizations applied. Here we report optical response in the form of the complex dielectric function (ε = ε 1 + iε 2 ) spectra of (FASnI 3 ) 1-x (MAPbI 3 ) x thin films over the spectral range from 0.74 to 5.89 eV.…”