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Defect engineering of solution-processed semi-transparent Kesterite solar cells (Advert Reference: RDF21/EE/MPEE/TIWARIDevendra)

   Faculty of Engineering and Environment

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  Dr D Tiwari, Dr G Zoppi  No more applications being accepted  Funded PhD Project (Students Worldwide)

About the Project

System-integrated photovoltaics (SIPV), i.e. integration of solar cells to buildings, automotive, etc., is a key emerging PV market projected to grow at an astounding rate of 15% over the next decade. Thin-film PV (TFPV) based on strong light-absorbing semiconductors can, in principle, produce sufficient power to drive solid-state lighting and sensing electronics for creating next-generation of smart windows and windshields. Furthermore, the low-fabrication temperatures of TFPV (typically < 600 oC) makes them compatible for processing on glass surfaces used in buildings and automotive. However, such applications require semi-transparent designs to retain lighting and viewing functionality.

Cu2ZnSn(S,Se)4, hereon referred to as Kesterite, composed of earth-abundant and low-cost elements, is currently being researched as a sustainable alternative absorber for future TFPV. Kesterite solar cells have already demonstrated power conversion efficiencies >12%. This project will investigate solution-processed Kesterite solar cells for semi-transparent PV. The use of sustainable materials along with solution-processing will allow high-throughput production of thin-film SIPV in a variety of non-flat geometries and at a minimal additional cost for extra functionality.

Realising fabrication of Kesterite solar cells for semi-transparent architecture poses several technical challenges. Conventional Kesterite devices are constructed on an opaque molybdenum metal layer, which acts as an electrical back-contact as well as a template for crystal growth of the absorber during the deposition. Semi-transparent device configuration, instead, requires using a transparent conductor as a back-contact, which might not form an Ohmic contact with the absorber layer and not be able to promote needed large-grain growth in the absorber. Additionally, the output voltage of conventional Kesterite devices is capped far below its theoretical limit due to a variety of point defects. Therefore, to reach high light-to-electrical power conversion, careful analysis of performance-limiting recombination pathways and complete re-design of device architecture and fabrication is needed via the following steps:

(i) Modification of back-contact transparent conductor to yield barrier-less electrical contact and to provide a template for crystal growth.

(ii) Tuning the solution-processing parameters, including the rheological properties of the molecular precursor, to be compatible with large-scale and high-throughput processing route and heat-treatment to achieve adherent, compact and crystalline Kesterite films on the modified substrates.

(iii) Exploiting strategies based on ad-atom dopants, alloying and compositional grading to selectively inhibit the formation of voltage-limiting defects and disorder within the bulk and at the interface while minimising non-radiative recombination.

The goal of this work will be to maximise the performance of PV devices with varying optical-transparency as sought for different of semi-transparent SIPV applications, such as electronic smart or PV integrated windows and automotive as well as mobile and low-power displays.

This is a highly interdisciplinary program utilising a variety of physical and chemical routes for thin-film and full solar PV device processing as well as advanced material characterisation based on the crystallographic, spectroscopic, photoelectrochemical, and electrical analysis. The research work will build upon the expertise of the supervisors and excellent new facilities device fabrication and testing within the Northumbria University Photovoltaics group.

The principal supervisor for this project is Dr. Devendra Tiwari.

Eligibility and How to Apply:
Please note eligibility requirement:
• Academic excellence of the proposed student i.e. 2:1 (or equivalent GPA from non-UK universities [preference for 1st class honours]); or a Masters (preference for Merit or above); or APEL evidence of substantial practitioner achievement.
• Appropriate IELTS score, if required.
• Applicants cannot apply for this funding if currently engaged in Doctoral study at Northumbria or elsewhere.

For further details of how to apply, entry requirements and the application form, see

Please note: Applications that do not include a research proposal of approximately 1,000 words (not a copy of the advert), or that do not include the advert reference (e.g. RDF21/EE/MPEE/TIWARIDevendra) will not be considered.
Deadline for applications: 29 January 2021
Start Date: 1 October 2021
Northumbria University takes pride in, and values, the quality and diversity of our staff. We welcome applications from all members of the community.

Funding Notes

The studentship is available to Home and International (including EU) students, and includes a full stipend, paid for three years at RCUK rates (for 2020/21, this is £15,285 pa) and full tuition fees.


[1] The Impact of Sb and Na doping on the surface electronic landscape of Cu2ZnSnS4 thin-films, Devendra Tiwari, Mattia Cattelan, Robert L. Harniman, Andrei Sarua, Neil Fox, Tristan Koehler, Reiner Klenk and David J Fermin, ACS Energy Letters 3 (2018) 2977–2982

[2] Mapping Shunting Paths at the Surface of Cu2ZnSn(S,Se)4 Films via Energy-Filtered Photoemission Microscopy, Devendra Tiwari, Mattia Cattelan, Robert L Harniman, Andrei Sarua, Ali Abbas, Jake W Bowers, Neil A Fox, David J Fermin, iScience 9 (2018) 36-46

[3] Spectroscopic and Electrical Signatures of Acceptor States in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells, Devendra Tiwari, Ekaterina Skidchenko, Jake Bowers, M. V. Yakushev, Robert Martin and David J Fermin, J. Mater. Chem. C 5 (2017) 12720-12727

[4] Cu2ZnSnS4 Thin Films Generated from a Single Solution Based Precursor: The Effect of Na and Sb Doping, Devendra Tiwari, T Koehler, X Lin, R Harniman, I Griffiths, L Wang, D Cherns, R. Klenk, DJ Fermín, Chemistry of Materials 28 (2016) 4991-4997