Manipulation of the Structure and Optoelectronic Properties through Bromine Inclusion in a Layered Lead Bromide Perovskite.

One of the great advantages of organic-inorganic metal halides is that their structures and properties are highly tuneable and this is important when optimizing materials for photovoltaics or other optoelectronic devices. One of the most common and effective ways of tuning the electronic structure is through anion substitution. Here, we report the inclusion of bromine into the layered perovskite [HN(CH)NH]PbBr to form [HN(CH)NH]PbBr·Br, which contains molecular bromine (Br) intercalated between the layers of corner-sharing PbBr octahedra.

Synthesis, Structure, and Tunability of Zero-Dimensional Organic-Inorganic Metal Halides Utilizing the -Xylylenediammonium Cation: MXDPbI, MXDBiI, and MXDBiBr·2HO.

Over the past decade, the efficiency of photovoltaic devices based on CHNHPbI have dramatically increased. This has driven research efforts in all areas, from the discovery of materials to film processing to long-term device stability studies. Here, we report the synthesis and structure of three new "zero dimensional" organic-inorganic metal halides which use the meta-xylylenediammonium (MXD) cation: MXDPbI, MXDBiI, and (MXD)BiBr·2HO.

Probing the structure-property-composition relationship in organic-inorganic tri-halide perovskites.

Here, we have synthesised a range of samples, with the formula (CH3NH3)1-2x(H3NC2H4NH3)xPbI3, with different levels of ethylenediammonium substitution to probe non-stoichiometry at the A-site of the perovskite. A single phase region was identified and is accompanied by a change in photophysical properties. The influence of aliovalent substitution with ethylenediammonium results in a decrease in HOMO level from -5.

An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7.

The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring and solving such structures which will be widely applicable to a range of functional materials. We exemplify the method with an investigation of the Bi2Sn2O7 pyrochlore, which has been shown to undergo transitions from a parent γ cubic phase to β and α structures on cooling.