Design, synthesis, structure analysis and photophysical characterization of robust and solution-processable one-dimensional copper(I) iodide-based inorganic-organic hybrid semiconductors

A series of new one-dimensional (1D) CuI-based inorganic-organic hybrid semiconductors have been designed and synthesized, namely, 1D-(dmpi)3Cu6I9 (1), 1D-(5asn)2Cu4I6 (2), 1D-(Nhex)2Cu4I6 (3) and 1D-(Npipz)2Cu2I6 (4) (dmpi = N,N-dimethylpiperidinium, 5asn = 5-azaspiro[4.4]nonan-5-ium, Nhex = cyclohexanaminium, Npipz = 1-methylpiperazine-1,4-diium). All structures are composed of ionically bonded aliphatic cations and various 1D CuI anionic copper iodide chains. Due to their wide bandgaps, all materials display ultraviolet (UV) emission between 340 and 390 nm, with internal quantum yields (IQYs) up to 6.4 %. All compounds are solution-processable due to their ionic bonding nature and have excellent thermal stability with their decomposition temperature (Td) up to 260 °C, as well as impressive air stability over long time periods. Due to the use of aliphatic cations as structure directing agents, the photophysical properties of these materials are dominated by their inorganic components, as confirmed by electronic structure calculations employing density functional theory (DFT). Additionally, their non-toxicity and facile synthesis suggest that this type of material is promising for practical use. These findings provide helpful insight into the future development of high-performance wide bandgap semiconductors that may be potentially useful in various UV-emitting or other optoelectronic applications.