Bioinspired Molecular Bridging in a Hybrid Perovskite Leads to Enhanced Stability and Tunable Properties

Abstract

Hybrid perovskites demonstrate high potential in optoelectronic applications. Their main drawback is their low stability under humid conditions. In this paper, one of nature's strategies is implemented-the incorporation of amino acids into the crystal lattice-in order to improve the stability of methylammonium lead bromide (MAPbBr 3) in water, and to tune its structure, as well as its optical and thermal properties. The amino acid lysine, which possesses two NH 3 + groups, is incorporated into the hybrid unit cell, by substituting two methylammonium ions and serves as a "molecular bridge". This incorporation induces a decrease in the lattice parameter of the host, accompanied with an increase in its bandgap and noticeable changes in its morphology. Furthermore, a substantial decrease in the thermal expansion coefficient of MAPbBr 3 and a shift of its cubic-to-tetragonal phase transformation temperature are observed. Two different modes of incorporation are identified, which depend on the conditions of crystallization. These modes dictate the level of lysine incorporation and the magnitude of MAPbBr 3 bandgap changes. Notably, lysine incorporation strongly increases the perovskite stability in water. This study demonstrates a unique and promising approach to tune the properties and improve the stability of hybrid perovskites via this novel bioinspired route.

Excessive Increase in the Optical Band Gap of Near‐Infrared Semiconductor Lead (II) Sulfide via the Incorporation of Amino Acids

“…The findings of this research validate the bioinspired route of band engineering via incorporation of AAs into NIR semiconductors. This study also further generalizes the bioinspired band gap engineering phenomenon for UV (ZnO [19,20] ), Vis (Cu 2 O [21] and MAPbBr 3 [22] ), and IR (PbS, this work) optical band gaps.…”

“…The observation of the band gap widening in the case of a semiconductor with a band gap in NIR range is a further corroboration of the bioinspired route to effectively tune the band gap of semiconductors, [ 23 ] and extends its validity to the IR regime. Moreover, here yet again the band gap is blueshifted as in all the other cases studied previoiusly, [ 19–23 ] and redshifted back after a mild annealing (Figure S2, Supporting Information). [ 19,21 ] These shifts strengthen the notion that the mechanism by which the incorporated AAs tune the hosts’ band gap is at least partly via quantum size effects due to the confinement of electrons and holes in between adjacent AAs in the host lattice.…”

Merging Biology and Photovoltaics: How Nature Helps Sun‐Catching

“…The champion device with n:8 showed PCEs of 18.05%, V OC s of 1.08 V, and J SC s of 22.9 mA cm −2 (Table 2). Another interesting effect was recently reported by Lang et al [374] The researchers investigated the effect of the amino acid l-lysine during the perovskite formation. While a comparable behavior was noticed, the authors also reported that amino acid additives strongly increase the perovskite stability in water.…”

Positively Charged Additives Facilitate Incorporation in Inorganic Single Crystals

“…Incorporation of amino acids in calcite (CaCO 3 ) enhances the hardness of the hybrid crystals, 2 while improved stability and increase in band gap are achieved for organometal halide perovskites and ZnO crystals. 8 − 10 The occlusion of functional nanoparticles is particularly attractive, as their properties can be predefined using well-established synthetic methods. For example, the incorporation of metal oxide nanoparticles 11 − 13 in KH 2 PO 4 and K 2 SO 4 has created single crystals for optoelectronic and photonic devices, while calcite-containing polymer nano-objects 14 and magnetic nanoparticles 15 exhibit enhanced physical properties.…”