Engineering electronic and optical properties of perovskites for light emission and solar cell applications

Abstract

2D Hybrid Organic Inorganic Perovskites (HOIPs) have gained popularity in the scientific community for their optoelectronic properties, stability and performance. 2D perovskites also possess novel qualities that may be exploited due to the removal of the constraints on the dimensions of the A-site spacer cation. Organic ligands with long carbon chains, diene groups and carboxylic acids may be used to amplify optoelectronic properties by means of topochemical polymerization via pressure [1]. Crosslinking between organic layers of perovskite have been associated with increased stability, lattice rigidity and enhanced carrier mobility. We investigate the properties of a novel compound (EtODA)2 PbBr4 under pressure with the objective of introducing cross-linking through topochemical polymerisation. (EtODA)2 PbBr4 is compared with poly-(EtODA)2 PbBr4 and characterised through Raman spectroscopy and photoluminescence spectroscopy. The organic moiety of (EtODA)2 PbBr4 has undergone irreversible phase transitioning with application of pressure, as made evident by the 785 nm Raman spectra. Additionally, multiple phase transitions at ~4 GPa and ~10GPa are observed in the inorganic lattice as characterised by the observations from Raman spectroscopy (532 nm and 633 nm) and photoluminescence spectroscopy. Polymerised (EtODA)2 PbBr4 is more resilient under pressure and does not undergo any phase changes with application of moderate pressure.