Perovskite and organic photovoltaics

Third generation thin-film photovoltaics (PV) are of significant interest for low-cost generation of solar electricity, as they potentially combine reduced embodied energy, with ease of manufacture using solution-based techniques.

At Sheffield, we have a detailed research programme into the development of photovoltaics based on two main types of semiconducting materials:

In both cases, such materials can be coated onto a surface using solution-based techniques, including spray-coating, and then fabricated into a PV device. We are currently exploring a range of different new perovskite and organic semiconductor materials, with our objective being to optimise device efficiency, maximise device stability and to develop techniques appropriate for device scale-up and manufacture.

In our research, we use a range of spectroscopic techniques to understand the electronic properties of the materials we develop, together with other structural probes (including X-ray scattering) to understand thin-film morphology over a range of length-scales. We also have an outdoors testing facility at the Sheffield Solar Farm. This acts as a long-term testing environment for photovoltaic devices made in the laboratory.

Selected publications

Ultrasonic Spray Deposition of a Passivating Agent for Spray-Coated, Methylammonium-Free Perovskite Solar Cells

Elena J. Cassella, Timothy Thornber, Robert D. J. Oliver, Mary E. O’Kane, Emma L. K. Spooner, Rachel C. Kilbride, Thomas E. Catley, Onkar S. Game, Alexandra J. Ramadan, David G. Lidzey

RRL Solar, 8, 2300814, 2024

We use ultra-sonic spray coating to passivate spray-cast CsFAbI3 perovskite solar cells using iso-butylammonium bromide. This process created a quasi-2D perovskite surface-layer and increased device open circuit voltage by 80 mV. Devices fabricated in this manner demonstrate power conversion efficiencies of up to 21.0%, with this work representing the first demonstration of a spray-coated surface passivation treatment that is compatible with high-throughput, roll-to-roll processing.

Perovskite solar cells

Low-Temperature, Scalable, Reactive Deposition of Tin Oxide for Perovskite Solar Cells

Dominic Blackburn, Thomas J. Routledge, Mary O’Kane, Elena J. Cassella, Onkar S. Game, Thomas E. Catley, Christopher J. Wood, Trevor McArdle, David George Lidzey.

RRL Solar, 6, 2270081, August 2022, DOI: 10.1002/solr.202270081

Tin oxide (SnOx) electron-extraction layers are fabricated via a reactive electron-beam evaporation process from a metal source under a partial pressure of oxygen. These are then used in standard (n-i-p) architecture perovskite solar cells and achieve power conversion efficiencies up to 19.3%.

The SnOx deposition process is performed onto substrates maintained at low temperature compared to similar techniques, with films not requiring any subsequent high-temperature post-deposition annealing. This demonstrates the potential compatibility of reactive electron-beam evaporation with roll-to-roll processing onto flexible polymeric substrates.

Air-Knife-Assisted Spray Coating of Organic Solar Cells

Emma L. K. Spooner, Elena J. Cassella, Joel A. Smith, Thomas E. Catley, Sam Burholt, and David G. Lidzey

ACS Appl. Mater. Interfaces 2023, 15, 33, 39625–39635

Ultrasonic spray coating is used to fabricate OSC devices based on a blend of the polymer PM6 with the Y-series acceptor DTY6. Using the non-halogenated solvent o-xylene, devices with PCEs of up to 14.1% are obtained. Wet film drying dynamics are controlled using an air-knife; a technique that has been demonstrated to be industrially scalable and has been used to “gas-quench” hybrid lead halide perovskite films in spray-coated cells and to assist drying in blade-coated OSCs.

Spray-coated perovskite solar cells

Nonplanar Spray-Coated Perovskite Solar Cells

Timothy Thornber, Onkar S Game, Elena J. Cassella, Mary E. O'Kane, James E. Bishop, Thomas J. Routledge, Tarek I. Alanazi, Mustafa Togay, Patrick J. M. Isherwood, Luis C. Infante-Ortega, Deborah B. Hammond, John M. Walls, David G. Lidzey.

ACS Appl. Mater. Interfaces 2022 Aug 24;14(33):37587-37594, DOI: 10.1021/acsami.2c05085

Ultrasonic spray coating is used to fabricate perovskite solar cells (PSCs) over rigid, nonplanar surfaces without problems caused by solution dewetting and subsequent “run-off”. We fabricate devices over a convex glass substrate, with devices having a maximum power conversion efficiency of 12.5%. To our best knowledge, this study represents the first demonstration of a rigid, curved perovskite solar cell. 

Gas-assisted spray coating of perovskite solar cells

Gas-Assisted Spray Coating of Perovskite Solar Cells Incorporating Sprayed Self-Assembled Monolayers (Adv. Sci. 14/2022)

Elena J. Cassella, Emma L. K. Spooner, Timothy Thornber, Mary E. O'Kane, Thomas E. Catley, James E. Bishop, Joel A. Smith, Onkar S. Game, David G. Lidzey.

Advanced Science, DOI:

Carbazole-based self-assembled monolayers are becoming a dominant hole-transporting layer in p-i-n perovskite solar cells, combining stability, efficiency, and low-cost. In article number 2104848 by David G. Lidzey and co-workers, spray coating and airbrush pen coating of MeO-2PACz is used to fabricate high-quality transport layers. This is combined with gas-quenched spray-coated perovskite layers, to realise solar cells with power conversion efficiencies in excess of 20%.

Perovskites on ice

Perovskites on Ice: An Additive-Free Approach to Increase the Shelf-Life of Triple-Cation Perovskite Precursor Solutions

M. E. O’Kane*, J. A. Smith, T. I. Alanazi, E. J. Cassella, Dr O. Game, Dr S. van Meurs, Professor D. G. Lidzey*.


Work described in this paper demonstrates that the shelf-life of high-performing perovskite precursors can be greatly improved by storing solutions at low-temperature without the need to alter chemical composition. The front cover of ChemSusChem (shown above) shows a futuristic view of large-scale perovskite solar cell (PSC) manufacture. This includes a high-volume roll-to-roll printing facility and cold-storage of PSC precursor solutions in large industrial fridges.

Development of spray-coated perovskite solar cells

Development of Spray-Coated Perovskite Solar Cells

James E. Bishop, Joel A. Smith, and David G. Lidzey*.

ACS Appl. Mater. Interfaces 2020, 12, 43, 48237-48245, DOI: 10.1021/acsami.0c14540

A look toward the future of spray-coating perovskite photovoltaics. Our spotlight on applications discusses developments made over the last six years that have enabled the fabrication of increasingly high-performance spray-coated perovskite solar cells.

In particular, the various approaches adopted to spray-cast perovskite films (one-step vs. two-step processes) ware charted and the development of sophisticated techniques used to control thin-film crystallinity is described. Finally, remaining research challenges are discussed that - once solved -may allow the mass deployment of low-cost solar energy.

Flexible back-contact perovskite solar micro-module

A flexible back-contact perovskite solar micro-module

Michael Wong-Stringer, Thomas J. Routledge, Trevor McArdle, Christopher J. Wood, Onkar S. Game, Joel A. Smith, James E. Bishop, Naoum Vaenas, David M. Coles, Alastair R. Buckley and David G. Lidzey.

Energy and Environmental Science, 2019, 6, DOI: 10.1039/c8ee03517b

In conjunction with Power Roll Ltd, EPMM have developed flexible, back-contact perovskite-based photovoltaic devices utilising a new, patented V-groove architecture. These devices are in principle easy to manufacture and do not include any rare-earth metals.

Advances in spray-cast perovskite solar cells

Advances in Spray-Cast Perovskite Solar Cells

James E. Bishop, Thomas J. Routledge, and David G. Lidzey.

J. Phys. Chem. Lett., 2018, 9, pages 1977-1984

This perspective summarises the developments in spray-cast perovskite solar cells made over the past few years, with particular attention paid to strategies employed to control the crystallisation of the perovskite. Steady progress has now been made with spray-cast perovskite PV devices recently demonstrated having a power conversion efficiency of 18.3%. We highlight trends within the research field and discuss challenges that will be necessary to drive such techniques toward practical application.

Light-soaking-free inverted polymer solar cells

Light-Soaking-Free Inverted Polymer Solar Cells with an Efficiency of 10.5% by Compositional and Surface Modifications to a Low-Temperature-Processed TiO2 Electron-Transport Layer

Yu Yan, Feilong Cai, Liyan Yang, Jinghai Li, Yiwei Zhang, Fei Qin, Chuanxi Xiong, Yinhua Zhou, David G. Lidzey, Tao Wang.

Advanced Materials, Volume 29, January 4 2017, 1604044

Lead halide perovskites

Open article: Mapping Morphological and Structural Properties of Lead Halide Perovskites by Scanning Nanofocus XRD

Samuele Lilliu, Thomas G. Dane, Mejd Alsari, Jonathan Griffin, Alexander T. Barrows, Marcus S. Dahlem, Richard H. Friend, David G. Lidzey, and J. E. Macdonald.

Advanced Functional Materials, Volume 26, Issue 45, pages 8221-8230, 12 October 2016

Polymer solar cells

Cover article: Polymer Solar Cells: Fabricating High Performance, Donor–Acceptor Copolymer Solar Cells by Spray-Coating in Air

Tao Wang, Nicholas W. Scarratt, Hunan Yi, Alan D. F. Dunbar, Andrew J. Pearson, Darren C. Watters, Tom S. Glen, Andrew C. Brook, James Kingsley, Alastair R. Buckley, Maximilian W. A. Skoda, Athene M. Donald, Richard A. L. Jones, Ahmed Iraqi and David G. Lidzey.

Advanced Energy Materials, Volume 3, Issue 4, page 410, April 2013

Advanced Functional Materials

Cover article: Correlating Structure with Function in Thermally Annealed PCDTBT:PC70BM Photovoltaic Blends

Tao Wang, Andrew J. Pearson, Alan D. F. Dunbar, Paul A. Staniec, Darren C. Watters, Hunan Yi, Anthony J. Ryan, Richard A. L. Jones, Ahmed Iraqi and David G. Lidzey.

Advanced Functional Materials, Volume 22, Issue 7, pages 1399-1408, April 10, 2012


Power Roll Ltd offers innovative energy storage and energy generation technologies

Ossila - enabling innovative electronics (spin out company from the EPMM group)

Ahmed Iraqi's research group

The Polymer Centre