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Folusho's review on layered hybrid perovskites is published

Congratulations to Helen on the publication of her first (joint) first author paper, which is a review of recent progress understanding how layered semiconducting perovskites can be designed and used in photovoltaic applications.

Layered Perovskites in Solar Cells: Structure, Optoelectronic Properties, and Device Design

Helen review

D. Sirbu, F. H. Balogun, R. L. Milot and P. Docampo
Advanced Energy Materials (May 2021)

Layered hybrid perovskites (LPKs) have emerged as a viable solution to address perovskite stability concerns and enable their implementation in wide-scale energy harvesting. Yet, although more stable, the performance of devices incorporating LPKs still lags behind that of state-of-the-art, multi-cation perovskite materials. This is typically assigned to their poor charge transport, currently caused by the choice of cations used within the organic layer. On balance, a compromise between efficiency and stability is sought, involving careful control of phase purity and distribution, interfaces and energy/charge transfer processes. Further progress is hindered by the difficulty in identifying the fundamental optoelectronic processes in these materials. Here, the high exciton binding energy of LPKs lead to the formation of multiple photoexcited species, which greatly complicate measurement interpretation. In this light, this review gives an overview of how complementary measurement techniques must be used to separate the contributions from the different species in order to identify device bottlenecks, and become a useful tool to narrow down the limitless list of organic cations. A move away from making compromises to mitigate the impact of poor charge transport is required. The root of the problem must be addressed instead through rational design of the interlayer cations.

Wed 09 Jun 2021, 11:47 | Tags: Paper

Real-time terahertz imaging with a single-pixel detector

Advances in THz imaging using spatial light modulation mean that a single-pixel detector can now image objects in real time. For more information see this press release and Rayko's paper in Nature Communications.

Fri 22 May 2020, 17:00 | Tags: Paper

Mobile charges and excitons in 1D radial van der Waals heterostructures

TOC figure2D sheets of atomically-thin materials have been intensively studied over the last few years, and have been found to bind together via van der Waals forces to create composites with unique optical and electronic properties. Here we report a study of the atomic structure and optoelectronic properties of some of the first examples of radial van der Waals heterostructures, where cylindrical sheets of different semiconductors (nanotubes) encase other materials. As described in our paper in Nano Letters, we found that BN overgrowth around carbon nanotube bundles created a good template for the creation of high-quality MoS2 nanotubes. This outer semiconducting wall had good electrical properties and strong optical absorption (including from the K-point excitons of MoS2), while the inner carbon nanotubes retained their excellent conductivity. This new class of composite may be suitable for unique functional optoelectronic devices on the nanoscale, such as 1D radial p-n junctions or transistors, for instance where the inner carbon nanotubes electrically control the outer semiconductor's conductivity.

Congratulations to Maria and the rest of the collaboration team (which included researchers at WCUS, Warwick Microscopy, the University of Tokyo and Aalto University).

Thu 30 Apr 2020, 07:50 | Tags: Paper

Congratulations to Hannah on her first paper

Hannah's first paper presents "A Robust Protocol for In Vivo THz Skin Measurements" and has just appeared in J. Infrared MM THz - check it out here!

Mon 09 Sep 2019, 09:30 | Tags: Paper

Negative photoconductivity in doped carbon nanotubes

Congratulations to Maria on the publication of her first paper from her PhD! Her work on the negative terahertz photoconductivity of controllably doped carbon nanotubes has just appeared in ACS Photonics - click here for more.

Wed 27 Mar 2019, 19:44 | Tags: Paper

A graphene-based terahertz modulator

graphene_device-xuequan_chen.jpg A joint collaboration between the Chinese University of Hong Kong and the University of Warwick has developed an efficient and broadband modulator of THz radiation. By reflecting THz radiation from a conductive, gated graphene layer the team have shown that the amplitude of THz radiation pulses can be modulated by more than 99%. Further, phase modulation was acheived by working above Brewster's angle. The findings are described in a recent article in Nature Communications, and are described in an article in Physics World.

Thu 29 Nov 2018, 08:53 | Tags: Paper

Vibrational properties of perovskite semiconductors using THz TF-TIR spectroscopy

Sun 2018

Congratulations to Sarah on the publication of her work on the vibrational properties of methylammonium lead halide perovskites, which you can read more about in J. Phys. Chem. C. In this work thin-film total internal reflection (TF-TIR) spectroscopy is shown to have an enhanced sensitivity to the vibrational properties of thin films in comparison to standard THz transmission spectroscopy. This increased sensitivity was used to track photoinduced modifications in the strengths of phonon modes under illumination.

Mon 06 Aug 2018, 14:07 | Tags: Paper

THz conductivity of double-walled carbon nanotube networks

summaryfigure.pngOur work on the conductivity of double-walled carbon nanotubes wrapped in xylan, a type of hemicellulose, has recently been published in Nanotechnology. Importantly the tubes were efficiently dispersed in water, and had excellent conductive properties. The hemicellulose was shown to not seriously interfere with the inter-tube conductance. This work was led by our collaborators in Finland at Jyvaskyla. Thanks to Maria & Connor for their efforts on our FTIR and THz-TDS results.

Tue 06 Feb 2018, 21:09 | Tags: Paper

Terahertz electromagnons as a probe of hysteresis and spin disorder in multiferroics

Congratulations to Connor on the publication of his recent work in a special issue of J. Phys. D: Applied Physics devoted to the applications of ultrafast spectroscopy. In this work we demonstrate that terahertz electromagnons can be used to directly probe the nature of a phase transition between magnetically ordered phases in the improper ferroelectric CuO.

Wed 17 Jan 2018, 08:05 | Tags: Paper

New paper on rotatable terahertz polarisation

Our recent work on creating a terahertz time-domain spectrometer with an arbitrarily rotatable, linear polarisation state has just been published in Scientific Reports. Congratulations to Connor and Michele on their work on this article. Read more here.

Wed 27 Sep 2017, 12:34 | Tags: Paper

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