Probing Strain-Induced Band Gap Modulation in 2D Hybrid Organic-Inorganic Perovskites - Supporting Information
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NORTHWESTERN UNIV EVANSTON IL EVANSTON United States
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In photovoltaics and flexible electronics applications, two-dimensional 2D hybrid organicinorganic perovskites HOIPs are often subjected to mechanical strain arising from materials processing, device functioning, and thermal expansion. Here we report for the first time a study of the band gap response to uniaxial tensile strain in thin 2D HOIP flakes with a general formula of CH3CH23NH32CH3-NH3n-1PbnI3n1. At large n n 3, the band gap will increase as the strain increases, and the strain response of band gap can be as high as 13.3 meV for n 5, which is due to the rotation of the inorganic PbI64- octahedra and the consequential Pb-I bond stretching and increase of Pb-I-Pb. Our findings provide a route to engineer the electronic properties of 2D HOIPs. The observed band gapstrain relationship can be harnessed to map the local mechanical strain in 2D HOIP-based devices and allow 2D HOIPs for sensing applications.
- Physical Chemistry