MoDCons: Multi-Modal Microscopy of Doped Semiconductors
Lead Research Organisation:
UNIVERSITY OF CAMBRIDGE
Department Name: Chemical Engineering and Biotechnology
Abstract
The development of efficient, low-cost, and durable doped semiconductors including photovoltaics, light-emitting diodes (LEDs) and
transistors will be central to the EU goal of reaching net-zero CO2 emissions by 2050. Taking photovoltaics as an example, the most
important aspects for commercialization are the power conversion efficiency (PCE), cost, and durability, which can be combined into
the levelized cost of electricity (LCOE) often expressed in euros per kilowatt hour. Multi-junction and bifacial
photovoltaics are therefore attractive because they enable power conversion limits associated with monofacial single junctions to be
surpassed, lowering the LCOE. MoDCons represents a departure from the broadly adopted strategy of "trial and error", instead driving
device engineering strategy with fundamental understanding. Dr Westbrook will achieved this by designing a multi-modal
microscopy toolkit capable of quantifying photophysical, chemical, and structural information on the microscale, in next-generation
semiconductors. He will deploy this toolkit to understand the structure-function relationships that underpin dopant formation in
mixed-metal halide perovskites, with implications for photovoltaics and other optoelectronics. Finally, he will use the multi-modal
microscopy toolkit to drive the device engineering of bifacial all-perovskite tandem solar cells to >30% efficiency and >1000h stability.
A major academic and industrial effort towards commercialization of next-generation photovoltaics and optoelectronics is currently
underway with its epicenter in Europe. Therefore, the postdoctoral fellowship represents a timely opportunity to return Dr
Westbrook from the United States to strengthen Europe's base in research and development. Through MoDCons, Dr Westbrook will
gain vital skills in device engineering, microscopy and management, securing his future independent academic career.
transistors will be central to the EU goal of reaching net-zero CO2 emissions by 2050. Taking photovoltaics as an example, the most
important aspects for commercialization are the power conversion efficiency (PCE), cost, and durability, which can be combined into
the levelized cost of electricity (LCOE) often expressed in euros per kilowatt hour. Multi-junction and bifacial
photovoltaics are therefore attractive because they enable power conversion limits associated with monofacial single junctions to be
surpassed, lowering the LCOE. MoDCons represents a departure from the broadly adopted strategy of "trial and error", instead driving
device engineering strategy with fundamental understanding. Dr Westbrook will achieved this by designing a multi-modal
microscopy toolkit capable of quantifying photophysical, chemical, and structural information on the microscale, in next-generation
semiconductors. He will deploy this toolkit to understand the structure-function relationships that underpin dopant formation in
mixed-metal halide perovskites, with implications for photovoltaics and other optoelectronics. Finally, he will use the multi-modal
microscopy toolkit to drive the device engineering of bifacial all-perovskite tandem solar cells to >30% efficiency and >1000h stability.
A major academic and industrial effort towards commercialization of next-generation photovoltaics and optoelectronics is currently
underway with its epicenter in Europe. Therefore, the postdoctoral fellowship represents a timely opportunity to return Dr
Westbrook from the United States to strengthen Europe's base in research and development. Through MoDCons, Dr Westbrook will
gain vital skills in device engineering, microscopy and management, securing his future independent academic career.
People |
ORCID iD |
Publications
Huang C
(2025)
Amphiphilic Polymer Conetworks for Non-Fullerene Organic Solar Cells: Regulated Molecular Stacking Enables Efficient Downconversion
in Advanced Energy Materials
| Description | Have set up a multi-modal microscopy workflow including steady-state and time-resolved photoluminescence, atomic force microscopy, nano X-ray fluorescence, and nano X-ray Diffraction. Have developed a technique for mapping the dopant density with sub-micron precision. In Sn-Pb perovskites, nanoscale regions of higher Sn content have red-shifted PL emission, and higher dopant densities. Scanning image microscopy shows that regions of higher dopant density have lower diffusion lengths. There are regions of high dopant density on the nanoscale that can't be identified with bulk techniques and may be performance-limiting (Einstein modelling predicts this). |
| Exploitation Route | This project has uncovered that the non-stoichiometric nanoscale distribution of tin and lead in mixed-metal perovskites (which occurs due to faster crystallization of the tin relative to the lead) leads to local differences in optoelectronic quality that ultimately limit device performance. We have also shown ways of lessening this heterogeneity e.g., with the use of additives or composition tuning. These key findings will be taken forward by process engineers, who will design next-generation additives, processes, and passivation treatments to counteract this heterogeneity and improve device performance. Given the relevance of lead-tin to commercially relevant all-perovskite tandem photovoltaics, this understanding may also be taken forward by start up companies to improve products. We have developed new methods for quantifying the dopant density, defect density, and other photophysical properties and mapping them on the nanoscale. These methods will be used by academics to assess material quality of different types of doped semiconductors (silicon, GaAs, perovskites) and could be rolled out as an in line metrology tool on assembly lines. |
| Sectors | Aerospace Defence and Marine Electronics Energy |
| Description | Scientific impact: MoDCons will inform the development of Sn-Pb perovskites by addressing a key issue blocking their development: performance loss due to self-doping and charge trap formation. The novel methods for probing and controlling doping employed here will have significance for the academic research of wide-gap Pb-based, and pure-Sn, PSCs. Furthermore, these strategies will be transferable to the fields of LEDs, FETs, photodetectors and thermoelectrics, all of which require intentional manipulation of the dopant density. The potential for high-impact in these areas is underlined by the amount of publications in the last few years (>30,000, >20,000 since 2022; Scopus). Economic and technological impact: MoDCons will develop quantitative microscopy methods that will improve the quality and capabilities of in-line metrology on semiconductor assembly lines, e.g. to determine microscale dopant levels. This is expected to be highly relevant to the commercialization of single-junction PSCs, as well as all-perovskite tandems and perovskite-on-silicon tandems, all of which are reported to contain moderate to strong dopant densities. Moreover, in-line metrology of dopant levels would be highly complementary to the development of LEDs and FETs made from perovskites and other semiconductor materials (e.g. silicon, MOS). Furthermore, adding the concept of bifaciality to all-perovskite solar cells should make them more competitive on the photovoltaics market, given that bifacial silicon solar cells are projected to increase market share to 60% by 2024. Societal impact: MoDCons will develop strategies to make more efficient semiconductors, including photovoltaics, LEDs and FETs. This effort will be in direct line with the European Green Deal, a key pillar of which is net carbon emission neutrality by 2050. Furthermore, the proposed research will advance a technology that will provide an effective power solution for off-grid communities worldwide, where still 770 million people do not have constant access to electricity. The experienced researcher and the host both have experience with engaging with rural communities in rural India and Ethiopia respectively about power-generation. |
| Sector | Aerospace, Defence and Marine,Electronics,Energy |
| Impact Types | Societal |
| Description | Junior Research Fellowship |
| Amount | £3,000 (GBP) |
| Organisation | University of Cambridge |
| Department | Wolfson College |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 01/2025 |
| End | 01/2028 |
| Description | Stranks-Rand collaboration |
| Organisation | Princeton University |
| Department | Princeton University Library |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | Advanced microscopic characterization of silver-doped perovskites (Westbrook) |
| Collaborator Contribution | Fabrication/processing of silver-doped perovskites (Westbrook) |
| Impact | Chemistry Physics Process Engineering Spectroscopy |
| Start Year | 2025 |
| Description | Westbrook-Lanzetta collaboration |
| Organisation | Jaume I University |
| Country | Spain |
| Sector | Academic/University |
| PI Contribution | Advanced microscopic characterization on Sn-Pb perovskites of different compositions (Westbrook) |
| Collaborator Contribution | Processing of Sn-Pb perovskites of different compositions (Lanzetta) |
| Impact | Robert Westbrook, Drivers for Photophysical Heterogeneity in Tin-Containing Halide Perovskites, MATUS Spring 2026, Barcelona (Invited Talk) Process Engineering Chemistry Physics |
| Start Year | 2024 |
| Description | Westbrook-MacDonald collaboration |
| Organisation | Diamond Light Source |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Advanced characterization of Sn-Pb perovskite films (Westbrook) |
| Collaborator Contribution | Fabrication/processing of Sn-Pb perovskite films (MacDonald) Support with measuring X-ray nanoprobe for XRF and XRD maps (Diamond i14) |
| Impact | Drivers for Photophysical Heterogeneity in Tin-Containing Halide Perovskites, MATUS Spring 2026, Barcelona (Invited Talk). Compositional Heterogeneity Drives Photophysics in Mixed-Metal Halide Perovskites, 2025 International Symposium on Sustainable Energy Applications of Advanced Solar and Hydrogen Technologies, National Chung Tsing University, Taichung, Taiwan (Invited Talk). Compositional Heterogeneity Drives Photophysics in Mixed-Metal Halide Perovskites, 2025 International Conference on Green Electrochemical Technologies, Tainan, Taiwan (Invited Talk). |
| Start Year | 2024 |
| Description | Westbrook-MacDonald collaboration |
| Organisation | University College London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Advanced characterization of Sn-Pb perovskite films (Westbrook) |
| Collaborator Contribution | Fabrication/processing of Sn-Pb perovskite films (MacDonald) Support with measuring X-ray nanoprobe for XRF and XRD maps (Diamond i14) |
| Impact | Drivers for Photophysical Heterogeneity in Tin-Containing Halide Perovskites, MATUS Spring 2026, Barcelona (Invited Talk). Compositional Heterogeneity Drives Photophysics in Mixed-Metal Halide Perovskites, 2025 International Symposium on Sustainable Energy Applications of Advanced Solar and Hydrogen Technologies, National Chung Tsing University, Taichung, Taiwan (Invited Talk). Compositional Heterogeneity Drives Photophysics in Mixed-Metal Halide Perovskites, 2025 International Conference on Green Electrochemical Technologies, Tainan, Taiwan (Invited Talk). |
| Start Year | 2024 |
| Description | Cambridge Festival - Make your Own Berry Solar Cell! |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | Devised and deployed an activity where >2000 members of the public have made their own solar cell from non-toxic ingredients such as berries, titanium dioxide and pencil scribblings. We will run the event again in March 2025, and I have appeared on departmental and central University of Cambridge social media (Tik Tok, instagram, Facebook) to promote the event. This is the most popular of around 20 events in the department for the Cambridge Festival and we receive very positive feedback from the public about solar cell fabrication (the audience are effectively 'solution processing' a solar cell, which is what we do in our labs with more advanced techniques) |
| Year(s) Of Engagement Activity | 2025,2026 |
| URL | https://www.eventbrite.co.uk/e/make-your-own-berry-solar-cell-tickets-1980456508730 |
| Description | Physics at Work |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | Delivered semiconductor workshops to >2000 UK school students via many 20 minute exhibits including 5 minute presentation, 15 minute 'hands on' berry solar cell fabrication session and 2 minutes of wrap up explaining how the solar cells work. There were lively debates throughout the activity and we received positive feedback from the schools that took part. |
| Year(s) Of Engagement Activity | 2024,2025 |
| URL | https://outreach.phy.cam.ac.uk/programme/physicsatwork |