Materials Make the Device — Colloidal Nanostructures for Solar Cells and Miniaturized Spectrometers

I am a chemist by education, trained by physicists, and now working as a materials scientist with an engineering mindset. My research is highly interdisciplinary, bridging fundamental materials discovery with real-world applications and industrial partners. Novel devices typically demand fundamental advances in materials, while a targeted research development of such materials benefits from industry-defined constraints. Bridging both, fundamental research and applications, enables a fast feedback loop between discovery and development. 

I will first introduce colloidal nanostructures — metal-oxide nanoparticles and quantum dots — which enable solution processing of crystalline semiconductors, precise surface engineering, and tuning of the light absorption through quantum confinement for the latter case. Following the materials introduction, their applications will be demonstrated within optoelectronic devices. 

Nanoscale photodetectors, based on colloidal quantum dots, can be developed and directly integrated into chip-sized miniaturized spectrometers.^[1] Embedded into smartphones or smartwatches, such devices would bring infrared spectroscopy into everyday life: on-the-go detection of pesticides in food, alcohol or drugs in beverages, continuous blood-sugar monitoring, and many other applications. Another rapidly emerging technology is perovskite solar cells and modules where the development is tremendously based on novel materials development. One promising route targets flexible, light-weight modules, in which perovskites are deposited by slot-die coating on roll-to-roll lines onto plastic foils. The challenge is striking: depositing 20-nm-thick semiconductor layers uniformly over square-meter areas demands extreme control over both the material and ink composition, so that fluid dynamics and the drying process remain uniform. Simplified materials syntheses help improving the control over the layer deposition, reproducibility, and reliability.^{[2, 3]}

I will close with an outlook on the planned activities of my research group over the next six years — spanning metal-oxide nanoparticle syntheses, organic semiconductor development, perovskite ink formulations, simplified solar-cell architectures, and advances in miniaturized spectrometers.

References

[1] M. J. Grotevent, S. Yakunin, D. Bachmann, C. Romero, J. R. V. de Aldana, M. Madi, M. Calame, M. V. Kovalenko, I. Shorubalko, “Integrated photodetectors for compact Fourier-transform waveguide spectrometers”, Nat. Photon. 2023, 17, 59–64. 

[2] M. J. Grotevent*, L. Kothe*, Y. Lu, C. J. Krajewska, M.-C. Shih, S. Tan, M. Tiemann, M. G. Bawendi, “Nontoxic and Rapid Chemical Bath Deposition for SnO₂ Electron Transporting Layers in Perovskite Solar Cells”, Chem. Mater. 2025, 37, 15, 5866–5873. *contributed equally.

[3] M. J. Grotevent, Y. Lu, T. Šverko, M.-C. Shih, S. Tan, H. Zhu, T. Dang, J. K. Mwaura, R. Swartwout, F. Beiglböck, L. Kothe, V. Bulović, M. G. Bawendi, “Additive-Free Oxidized Spiro-MeOTAD Hole Transport Layer Significantly Improves Thermal Solar Cell Stability”, Adv. Energy Mater. 2024, 2400456.