Band-Gap Tuning in All-Inorganic CsPbxSn1-xBr3 Perovskites

• Published in: ACS applied materials & interfaces Vol. 13; no. 3; pp. 4203 - 4210
• Main Authors: Schwartz, Heidi A, Laurenzen, Hannah, Marzouk, Asma, Runkel, Manuel, Brinkmann, Kai Oliver, Rogalla, Detlef, Riedl, Thomas, Ashhab, Sahel, Olthof, Selina
• Format: Journal Article
• Language: English
• Published: 27.01.2021
• Subjects: films (materials); light emitting diodes; materials; spectroscopy
• ISSN: 1944-8252; 1944-8252
• DOI: 10.1021/acsami.0c20285

We investigate all-inorganic perovskite CsPbxSn1-xBr3 thin films to determine the variations in the band gap and electronic structure associated with the Pb/Sn ratio. We observe that the band gap can be tuned between 1.86 eV (x = 0) and 2.37 eV (x = 1). Intriguingly, this change is nonlinear in x, with a bowing parameter of 0.9 eV; furthermore, a slight band gap narrowing is found for low Pb content (minimum x ∼ 0.3). The wide tunability of the band gap makes CsPbxSn1-xBr3 a promising material, e.g., for a wide-gap subcell in tandem applications or for color-tunable light-emitting diodes. Employing photoelectron spectroscopy, we show that the valence band varies with the Pb/Sn ratio, while the conduction band is barely affected.We investigate all-inorganic perovskite CsPbxSn1-xBr3 thin films to determine the variations in the band gap and electronic structure associated with the Pb/Sn ratio. We observe that the band gap can be tuned between 1.86 eV (x = 0) and 2.37 eV (x = 1). Intriguingly, this change is nonlinear in x, with a bowing parameter of 0.9 eV; furthermore, a slight band gap narrowing is found for low Pb content (minimum x ∼ 0.3). The wide tunability of the band gap makes CsPbxSn1-xBr3 a promising material, e.g., for a wide-gap subcell in tandem applications or for color-tunable light-emitting diodes. Employing photoelectron spectroscopy, we show that the valence band varies with the Pb/Sn ratio, while the conduction band is barely affected.