Phenothiazine-benzimidazole architecture as an efficient interfacial charge transport layer for perovskite blue light emitting diodes
Proceedings of SPIE - Volume 11894, Optoelectronic Devices and Integration X SPIE 11894 (2021)
Abstract:
Solution-processed metal halide perovskite light-emitting diodes (Pe-LEDs) show great promise in a range of optoelectronic applications. However, these devices can be limited by poor interfaces to the perovskite films due to poor crystallization control during film processing caused by de-wetting from the bottom layer. The deep (Highest Occupied Molecular Orbital) HOMO levels of the emitters also lead to large charge injection barriers for standard electrodes. To improve this, we develop and report on a small molecule, BPS2, based on phenothiazine-benzimidazole with Lewis base sites. This promising interfacial material is then applied to blue PeLEDs where the energy band alignment of BPS2 to the blue perovskite emitter helps to reduce the hole-injection barrier while blocking electrons. BPS2 can be solution-processed with non-chlorinated organic solvents and provides improved wettability towards perovskite precursor solutions compared to conventional PEDOT:PSS hole transport films. A thin interlayer of BPS2 introduced between PEDOT:PSS and a perovskite emission layer is shown to improve both the device external quantum efficiency and luminance in comparison to the reference device without the interlayer.Understanding hierarchical spheres-in-grating assembly for bio-inspired colouration
Materials Horizons Royal Society of Chemistry 8:8 (2021) 2230-2237
Abstract:
The vivid iridescent response from particular butterflies is as an excellent example of how micro-engineered hierarchical architectures that combine physical structures and pigmentary inclusions create unique colouration. To date, however, detailed knowledge is missing to replicate such sophisticated structures in a robust, reliable manner. Here, we deliver spheres-in-grating assemblies with colouration effects as found in nature, exploiting embossed polymer gratings and self-assembled light-absorbing micro-spheres.Highly deformed o-carborane-functionalised non-linear polycyclic aromatics with exceptionally long C-C bond lengths
Chemistry - A European Journal Wiley 27:6 (2020) 1970-1975
Abstract:
The effect of substituting o‐carborane into the most sterically hindered positions of phenanthrene and benzo(k)tetraphene is reported. Synthesised via a Bull‐Hutchings‐Quayle benzannulation, the crystal structures of these non‐linear polycyclic aromatics exhibited the highest aromatic deformation parameters observed for any reported carborane compound to date, with the largest carboranyl C‐C bond length of all organo‐substituted o ‐carboranes. Photoluminescence studies of these compounds demonstrated efficient intramolecular charge‐transfer, leading to aggregation induced emission properties. Additionally, an unusual low‐energy excimer was observed for the phenanthryl compound. These are two new members of the family of carborane‐functionalised non‐linear polycyclic aromatics notable for their peculiar structures and multi‐luminescent properties.Correlating the Structural and Photophysical Properties ofOrtho,Meta, andPara-Carboranyl-Anthracene Dyads
ADVANCED ELECTRONIC MATERIALS (2020) ARTN 2000312
A metallic hot-carrier photovoltaic device
Semiconductor Science and Technology IOP Publishing 34:6 (2019) 064001-064001