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Layered Germanium Hybrid Perovskite Bromides: Insights from Experiments and First‐Principles Calculations
Author(s) -
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
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201903528
Subject(s) - perovskite (structure) , germanium , halide , materials science , band gap , lone pair , diode , metal , optoelectronics , nanotechnology , inorganic chemistry , crystallography , molecule , organic chemistry , chemistry , silicon , metallurgy
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 (CH 3 (CH 2 ) 3 NH 3 ) 2 (CH 3 NH 3 ) n −1 Ge n Br 3 n +1 is investigated, derived from the parent 3D ( n = ∞) CH 3 NH 3 GeBr 3 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.