Dr Joshua Reding
Academic and research departments
Advanced Technology Institute, Faculty of Engineering and Physical Sciences.About
My research project
Excited State Properties of Two-Dimensional Lead Halide PerovskitesMy research focus is in examining the electronic environment of two-dimensional lead halide perovskites. Lead halide perovskites are an emerging material field in solar cells, LEDs, and other optoelectronic devices. By chemically engineering the stochiometry of the perovskite structure, electronically isolated monolayers can be formed in which diffusion is limited to a single plane. Current studies involve examing the evolving environment of mixed halide perovskites using transient absorption spectroscopy and density functional theory. The aim is to improve the selection of materials of for optoelectronic applications by establishing a more complete view of the evolution of excited state carriers.
Supervisors
My research focus is in examining the electronic environment of two-dimensional lead halide perovskites. Lead halide perovskites are an emerging material field in solar cells, LEDs, and other optoelectronic devices. By chemically engineering the stochiometry of the perovskite structure, electronically isolated monolayers can be formed in which diffusion is limited to a single plane. Current studies involve examing the evolving environment of mixed halide perovskites using transient absorption spectroscopy and density functional theory. The aim is to improve the selection of materials of for optoelectronic applications by establishing a more complete view of the evolution of excited state carriers.
Publications
Highlights
Imaging Excited-State Dynamics in Two-Dimensional Semiconductors with Emerging Ultrafast Measurement Techniques
Successful manipulation of halide perovskite surfaces is typically achieved via the interactions between modulators and perovskites. Herein, it is demonstrated that a strong-interaction surface modulator is beneficial to reduce interfacial recombination losses in inverted (p-i-n) perovskite solar cells (IPSCs). Two organic ammonium salts are investigated, consisting of 4-hydroxyphenethylammonium iodide and 2-thiopheneethylammonium iodide (2-TEAI). Without thermal annealing, these two modulators can recover the photoluminescence quantum yield of the neat perovskite film in contact with fullerene electron transport layer (ETL). Compared to the hydroxyl-functionalized phenethylammonium moiety, the thienylammonium facilitates the formation of a quasi-2D structure onto the perovskite. Density functional theory and quasi-Fermi level splitting calculations reveal that the 2-TEAI has a stronger interaction with the perovskite surface, contributing to more suppressed non-radiative recombination at the perovskite/ETL interface and improved open-circuit voltage (V-OC) of the fabricated IPSCs. As a result, the V-OC increases from 1.11 to 1.20 V (based on a perovskite bandgap of 1.63 eV), yielding a power conversion efficiency (PCE) from approximate to 20% to 21.9% (stabilized PCE of 21.3%, the highest reported PCEs for IPSCs employing poly[N,N ''-bis(4-butylphenyl)-N,N ''-bis(phenyl)benzidine] as the hole transport layer, alongside the enhanced operational and shelf-life stability for unencapsulated devices.