Light Emission

The light-emission subgroup is involved in a diverse range of projects focused on exploring and advancing various aspects of perovskite-based light-emitting diodes (PeLEDs) and X-ray detection technologies. Their research encompasses both fundamental understanding and practical device applications. Here is an overview of the different projects within the group.

Perovskite LED

  1. We work at the device level to turn new emitters into high-performance light-emitting systems. We collaborate closely with the materials and spectroscopy subgroups, translating accelerated material optimisation and spectroscopic findings into brighter emitters and more robust devices. Using both solution-processing and vapour phase deposition, we span across the entire visible spectrum, primarily blue, green, and red colours, with the ultimate goal including efficient systems for white-lighting and high light amplification for lasing. We combine both transport layer engineering and additive engineering to tune charge injection and balance through band alignment, morphology, film formation control for higher efficiency and stability. To pinpoint loss mechanisms, we have developed correlated imaging tools that allow us to quantify static and transient photo-, electro- and mechano-luminescence heterogeneities on the nanoscale and compare those with their structural/chemical/morphological information. These methodologies are key to understand the origin of performance losses and develop new strategies to overcome those losses. 

Perovskite LED

 

Related publications:

  1. Lu, Y.; Jung, Y.-K.; Dubajic, M.; Li, X.; Maqbool, S.; Gu, Q.; Bai, X.; Boeije, Y.; Chua, X. W.; Mirabelli, A. J.; Kang, T.; Sonneveld, L.; Zhang, Y.; Selby, T. A.; Mamak, C.; Tang, K.; Yu, Z.; Liu, T.; Anaya, M.; Barlow, S.; Marder, S. R.; Ehrler, B.; Ducati, C.; Friend, R. H.; Stranks, S. D. Layer-by-layer Epitaxial Growth of Perovskite Heterostructures with Tunable Band Offsets, Science 2025, In Press | Accepted Version

  2. Jeong, H. I.; Choi, S. E.; Chua, X. W.; Kim, N. W.; Pyrilli, E.; Lee, H.; Kang, D.-W.; Lee, B. R.; Stranks, S. D.; *Kim, J.; *Bandyopadhyay, S.; *Choi, H. High-Resolution Mechanoluminescent Haptic Sensor via Dual-Functional Chromatic Filtration by a Conjugated Polymer Shell, Adv. Mater. 2025, In Press, DOI:10.1002/adma.202508917 

  3. Jeong, H. -I.; Jung, H. -H.; Dubajic. M.; Kim, G.; Jeong, W. -H.; Song, H.; Lee, Y.; Biswas, S.; Kim, H.; Lee, B. -R.; Woong Yoon, J.; *Stranks, S. D.; *Jeong, S. –M.; *Lee, J.; Choi, H. Super elastic and negative triboelectric polymer matrix for high performance mechanoluminescent platforms Nat. Commun. 2025, 16, 854

  4. Chen, J. Ji, K.; Dai, L.; Xiang, G.; Yu, Z.; Iqbal, A. N.; Wang, J.; Ma, X.; Guo, R.; Anaya, M.; Song, X.; Lu, L.; Chiang, Y. -H.; Li, W.; Shen, Y.; Luo, X.; Mirabelli, A.; Cheng, Y.; Chen, X.; Ma, D.; *Fan, Z.; *Yang, Y.; *Duan, L.; *Stranks, S. D.; *Zeng. H. Nanoscale Heterophase Regulation Enables Sunlight-like Full-spectrum White Electroluminescence Nat. Commun. 2025, 16, 3621

  5. Kong, L.; Sun, Y.; Zhao, B.; Ji, K.; Feng, J.; Dong, J.; Wang, Y.; Liu, Z.; Maqbool, S.; Li, Y.; Yang, Y.; Dai, L.; Lee, W.; Cho, C.; Stranks, S. D.; Friend, R. H.; *Wang, N.; *Greenham, N. C.; *Yang, X. Fabrication of red-emitting perovskite LEDs by stabilizing their octahedral structure Nature 2024, 631, 73–79

  6. Yuan, S.; Dai, L.; Sun, Y.; Auras, F.; Zhou, Y-H.; An, R-Z.; Liu, Y.; Ding. C.; Cassidy, C.; Tang, X.; Dong, S-C.; Kang, H-B.; Chen, K.; Liu, X.; Ye, Z-F.; Zhao, Y.; Adachi, C.; Liao, L-S.; Greenham, N. C.; Qi, Y.; *Stranks, S. D.; *Cui, L-S.; Friend, R.H. Efficient blue electroluminescence from reduced-dimensional perovskites Nat. Photon. 2024, 18, 425-431

  7. Sun, Y. et al. Bright and stable perovskite light-emitting diodes in the near-infrared range. Nature 2023, 615, 830–835

  8. Shen, X.; Kang, K.; Yu, Z.; Jeong, W. H.; Choi, H.; Park, S. H.; *Stranks, S. D.; *Snaith, H. J.; *Friend, R. H.; *Lee, B. R. Passivation strategies for mitigating defect challenges in halide perovskite light-emitting diodes Joule 2023, 7(2), 272-308

 

2. 

We employ advanced modelling tools to simulate light-matter interactions and find the best device architectures for PeLEDs, along with optimizing the charge transport layer and composition of the perovskite layer for enhanced emission, better colour purity, control over directionality, white emission etc.

Related publications:

  1. Ooi, Z. Y.; Nie, S.; Vega, G.; Lai, M. C.; Jiménez-Solano, A.; Huang, C.-S.; Wang, H.; Liu, T.; Gałkowski, K.; Nowak, M. P.; Nyga, P.; Cheng, Q.; Ducatí, C.; Carretero-Palacios, S.; Kahmann, S.; *Stranks, S. D.; *Anaya, M. Resonant cavity effect for spectrally tunable and efficient narrowband perovskite photodetectors ACS Photon. 2025, 12(8), 4119–4129

  2. Ooi, Z.Y; Jiménez-Solano, A; Gałkowski, K; Sun, Y; Orri, J.F; Frohna, K; Salway, H; Kahmann, S; Nie, S; Vega, G; Kar, S; Nowak, M.P; Maćkowski, S; Nyga, P; Ducati, C; Greenham, N.C; Lotsch, B.V; *Anaya, M; *Stranks, S. D. Strong angular and spectral narrowing of electroluminescence in an integrated Tamm-plasmon-driven halide perovskite LED Nat. Commun. 2024, 15, 5802

 

3. LED degradation/device physics

Improving operational stability remains one of the most critical challenges of perovskite LEDs. Using various in-situ tools, we uncover where and how the device degrade under electrical stress, elucidate failure pathways, and providing insights into new design rules. We employ advanced characterization techniques to investigate the impact from interfaces and device structure, and optimize thin film fabrication protocols for improved performance. Our toolkit combines diffraction, photoemission, and ultrafast spectroscopy, including GIWAXS, HAXPES, electron microscopy, transient photoluminescence (trPL) spectrometer, transient absorption (TA) spectrometer, and UV-vis absorption spectrometer.

 

Related publications:

  1. Mirabelli, A. J.; Kammlander, B.; Lu, Y.; Varma, R. M.; Gu, Q.; Radetzky, K.; Selby, T. A.; Liu, T.; Riva, S.; Wei, Z.; Lee, T.-L.; Rawle, J.; Rensmo, H.; Anaya, M.; *Cappel, U. B.; *Stranks, S. D. Interfacial Chemistry Limits the Stability of Deep Blue Perovskite LEDs Revealed by Operando Characterisation ACS Energy Lett. 2025, 10, 3533–3543

  2. Ji, K. et al. Self-supervised deep learning for tracking degradation of perovskite light-emitting diodes with multispectral imaging. Nat. Mach. Intell. 2023 doi:10.1038/s42256-023-00736-z

  3. Jung, Y. K.; Abdulla, M.; Friend, R. H.; *Stranks, S.; *Walsh, A. Pressure-induced non-radiative losses in halide perovskite light-emitting diodes J. Mater. Chem. C 2022, 10, 12560-12568

  4. Andaji‐Garmaroudi, Z. et al. Elucidating and Mitigating Degradation Processes in Perovskite Light‐Emitting Diodes. Adv. Energy Mater. 2020, 10, 2002676

 

 

X/γ -ray detector

We use a 150 kV microfocus X-ray source housed within a fully interlocked X-ray chamber to evaluate the detection performance of our devices and to perform X-ray Computed Tomography (CT). The chamber includes two precision motion stages: a sample stage capable of 360° rotation and movement in the x–y plane, and a detector stage with full three-dimensional positioning. The X-ray tube’s focal spot can be reduced to as small as 5 µm, enabling highly precise and high-resolution measurements.

 

Xray Detector

We operate a photon-counting measurement setup comprising sealed radioactive sources and dedicated pulse-processing electronics. This system is central to our research on applying our detectors for photon-counting computed tomography (PCCT). It enables precise characterization of key device metrics, including energy resolution, µτ product, and charge carrier mobility. Our gamma-ray sources provide characteristic emission peaks at 59.5 keV, 122 keV, and 662 keV, covering a wide energy range for applications in medical imaging to security screening, while our alpha particle source emits at 5.5 MeV.

 

Particle Source

 

Scintillator physics

We employ a wide range of experimental diagnostics for characterising scintillation physics in different materials. Our primary in-house tool is the Edinburgh Instruments FLS-1000 spectrometer coupled to an X-ray chamber, equipped with both continuous wave and pulsed X-ray sources. We measure dose-rate dependent radioluminescence covering UV, visible, NIR, and IR wavelength ranges as well as time-resolved radioluminescence from the ns-time scale to as long as ms-decay times. We also regularly do experiments at synchrotron facilities such as the Diamond Light Source, measuring radioluminescence quantum yield, X-ray absorption spectroscopy with in-situ radioluminescence, vacuum UV luminescence excitation, and more.

 

Scintillator physics

 

Radio-photovoltaics

In addition to gamma-ray and X-ray detection, we also work on gamma-ray and X-ray harvesting through research on radio-photovoltaic devices such as gammavoltaics and X-ray-voltaics. Radioisotope gamma-ray harvesting poses a potential alternative to traditional radioactive thermoelectric generators for low-power, solid-state power sources for deep space and remote applications. These devices utilize high-light yield single crystal scintillators with large Stokes shifts to convert gamma radiation to a high multiplicity of visible or NIR photons for spectrally tuned photovoltaic harvesting. In contrast to radiovoltaic devices, the scintillator interface in radio-photovoltaics decouples gamma-ray absorption from charge extraction by instead extracting sub-bandgap scintillation photons. Experiments are performed using X-ray irradiation in our labs as well as ultra-high-activity gamma irradiation at the Paul Scherrer Institute (PSI) gamma irradiation facility.

Radio-Photovoltaics

Related publications:

  1. Moseley, O. D. I., Doherty, T. A. S., Parmee, R., Anaya, M. & Stranks, S. D. Halide perovskites scintillators: unique promise and current limitations. J. Mater. Chem. C 2021, 9, 11588–11604
  2. Ferrer Orri, J. et al. Unveiling the Interaction Mechanisms of Electron and X‐ray Radiation with Halide Perovskite Semiconductors using Scanning Nanoprobe Diffraction. Adv. Mater. 2022, 34, 2200383
  3. Wei, Z. et al. Carrier Diffusion Links Single Crystal Quality and Photoluminescence in Halide Perovskite Radiation Detectors Advanced Materials 2025, e12302
  4. Imam, S., Phan, Q.V., Wei, Z., Bayikadi, K.S., Stranks, S.D., Kanatzidis, M.G. Spectroscopic Performance of CsPbBr3 Perovskite γ-Ray Detectors Despite Grain Boundaries 2026, e18137