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Projects: Projects for Investigator
Reference Number EP/R044481/1
Title Unravelling ultrafast charge recombination and transport dynamics in hybrid perovskites.
Status Completed
Energy Categories Renewable Energy Sources(Solar Energy, Photovoltaics) 50%;
Energy Efficiency(Residential and commercial) 50%;
Research Types Basic and strategic applied research 100%
Science and Technology Fields PHYSICAL SCIENCES AND MATHEMATICS (Physics) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Professor Sir R Friend
No email address given
University of Cambridge
Award Type Standard
Funding Source EPSRC
Start Date 01 October 2018
End Date 31 March 2021
Duration 30 months
Total Grant Value £328,463
Industrial Sectors Energy
Region East of England
Programme NC : Infrastructure, NC : Physical Sciences
Investigators Principal Investigator Professor Sir R Friend , Physics, University of Cambridge (100.000%)
Web Site
Abstract The photoluminescence (PL) efficiency of the hybrid perovskites are exceptionally high for a poly-crystalline semiconductor. I was the first to report this, as exemplified by lasing in vertical cavity structure, and I have gone on to demonstrate that the strong radiative emission is key for the perovskites' exceptional performance in solar cells (power conversion efficiency >20% reported) and light-emitting diodes (external quantum efficiency now >18% in our labs). Future gains will require understanding and control of the non-radiative losses both in the bulk and at the electrodes. Our initial results showed that the PL arises from the recombination of free charges, but new physical concepts are now required to understand how this process can give such unexpectedly high radiative yields, while maintaining low non-radiative losses. The reported long lifetimes bring much longer length scales into play, compared to typical high-emission III-V quantum-well systems. Material inhomogeneity is a central parameter, since electrons and holes sample large volumes before recombination, which potentially changes their physical properties and interactions.State-of-the art PL studies recorded spatially-averaged information with time-resolution around 100 ps, due to challenges in recording local signals on short timescales. Yet, we have found carrier interactions already on sub-picosecond times, which are likely to affect recombination at longer time scales. Probing PL at these fast timescales, will now give insights into a new physical regime. For this, our new technique will combine ultrafast spectrally-resolved PL with spatial microscopy, which will advance the state-of-the art in temporal and spatial resolution by an order of magnitude to sub-picosecond and sub-micrometre regimes. We will use this new setup to study carrier recombination and diffusion in a regime dominated by intrinsic properties (controlled by the carrier-carrier interactions), which will allow us to untangle extrinsic effects (controlled by material properties such as trapping). Simultaneously, local probing will resolve the impact of material morphology on recombination and localisation.Our study will give unprecedented insights into the photo-physics of hybrid perovskites in previously inaccessible, yet highly relevant, temporal and spatial regimes. Our findings will establish a new picture on the physical and material origin enabling the exceptionally-efficient radiative recombination in hybrid perovskites, which will be crucial for unlocking gains in device performance.
Publications (none)
Final Report (none)
Added to Database 28/03/19