Layered Germanium Hybrid Perovskite Bromides: Insights from Experiments and First‐Principles Calculations. (6th June 2019)

• Record Type: Journal Article
• Authors: Chang, Xueqing; Marongiu, Daniela; Sarritzu, Valerio; Sestu, Nicola; Wang, Qingqian; Lai, Stefano; Mattoni, Alessandro; Filippetti, Alessio; Congiu, Francesco; Lehmann, Alessandra Geddo; Quochi, Francesco; Saba, Michele; Mura, Andrea; Bongiovanni, Giovanni
• Is Part Of: Advanced functional materials. Volume 29:Number 31(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-06-06
• Subjects: ferroelectricity -- germanium -- hybrid perovskites -- lead‐free -- optical properties; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201903528
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Metal halide perovskites are maturing as materials for efficient, yet low cost solar cells and light‐emitting diodes, with improving operational stability and reliability. To date however, most perovskite‐based devices contain Pb, which poses environmental concerns due to its toxicity; lead‐free alternatives are of importance to facilitate the development of perovskite‐based devices. Here, the germanium‐based Ruddledsen–Popper series (CH3 (CH2 )3 NH3 )2 (CH3 NH3 ) n −1 Ge n Br3 n +1 is investigated, derived from the parent 3D ( n = ∞) CH3 NH3 GeBr3 perovskite. Divalent germanium is a promising, nontoxic alternative to Pb 2+ and the layered, 2D structure appears promising to bolster light emission, long‐term durability, and moisture tolerance. The work, which combines experiments and first principle calculations, highlights that in germanium bromide perovskites the optical bandgap is weakly affected by 2D confinement and the highly stereochemically active 4s 2 lone pair preludes to possible ferroelectricity, a topic still debated in Pb‐containing compounds. Abstract : Germanium bromide hybrid perovskites are demonstrated as a promising, nontoxic alternative to lead‐based ones. The Ruddledsen–Popper series (CH3 (CH2 )3 NH3 )2 (CH3 NH3 ) n −1 Ge n Br3 n +1 is studied with a combination of experiments and first principle calculations, highlighting the peculiarity of this materials class, where the optical bandgap is weakly affected by 2D confinement and the highly stereochemically active 4s 2 lone pair preludes to ferroelectricity.