Irreversible Lattice Compression Lights Up Perovskites
Karunakara Moorthy Boopathi a, Beatriz Martin-Garcia a, Aniruddha Ray a, Liberato Manna a, Ahmed Abdelhady a
a Istituto Italiano di Tecnologia - IIT
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Ahmed Abdelhady, presentation 059
Publication date: 25th November 2019

Lattice compression of the halide perovskites due to mild mechanical pressure results in decreased bandgap, enhanced photoluminescence (PL), longer carrier lifetime, and reduced trap-states.[1] However, these effects are lost upon decompression. Therefore, developing irreversible lattice compression is needed in order to preserve the enhanced optoelectronic properties. Here, we grow high-quality methylammonium lead bromide (MAPbBr3) single crystals by developing an antisolvent-assisted solvent acidolysis crystallization technique. The crystals show intense emission at all four edges under UV lamp. Using micro-X-ray diffraction, we examine the structural differences at the edges and central regions; concluding that the enhanced edges emission is due to lattice compression.The structural changes between the edges and the central areas are also confirmed by macro- and micro-PL, and Raman spectroscopy studies. As a consequence of the lattice compression, shallower trap states and/or reduced trap state densities at the edges are expected. In fact, time-resolved PL measurements show 20 times longer photogenerated carriers lifetimes at the edges compared to the central areas. Furthermore, light detectivity is five times enhanced at the compressed edges with respect to the unstrained central regions. Our findings indicate that developments toward realizing the theoretical limit of radiative recombination in the perovskite-based optoelectronic devices could be achieved through a controlled crystallization process where both structural defects and non-radiative pathways can be reduced.

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