Masaru K. Kuno

Research Interests

Nanoscience and nanotechnology are premised on exploiting the size- and shape-dependent optical, electrical, and chemical properties of materials for applications. Among proposed applications of nanostructured semiconductor materials are light emitting, light harvesting, and cooling. At microscopic scales, local variations in optical, electrical, and chemical responses exist, and these can be used to characterize material properties.

The Kuno Group has therefore developed microscopic approaches for probing material behavior on small length scales. This has entailed conducting some of the first single nanostructure extinction experiments. The importance of being able to probe extinction as opposed to emission lies in the fact that many materials are not particularly emissive. Consequently, they are effectively invisible to existing single particle and single molecule optical measurements based on photoluminescence. More recent single nanostructure absorption studies have focused on conducting experiments in the mid-infrared “fingerprint” region of the spectrum. This enables ultrasensitive, chemically specific imaging and spectroscopy of individual nanostructures and other materials such as micro/nanoplastics.

Another important theme in our research involves unravelling the photophysics of important materials. One example involves mixed-halide hybrid perovskite materials used in solar energy conversion, e.g., tandem perovskite/silicon solar cells. Despite record setting solar power conversion efficiencies, the mixed-halide perovskite active layers of such devices are subject to unwanted, light-induced halide photosegregation. Understanding these intrinsic material instabilities is crucial for eventually commercializing perovskite-based devices. Efforts have therefore been made to develop a microscopic model of light-induced halide photosegregation using detailed optical studies of photosegregation coupled to theory.

Finally, a long term goal is to realize the optical refrigeration of semiconductors. The concept was first conceived in 1929 and is based on the simple premise that photoluminescence up-conversion can remove heat from materials. Preventing realization of this concept, however, are material quality issues that lead to irradiation-induced heating overwhelming cooling. We have focused on solving these material quality issues and on developing a fundamental understanding of photoluminescence up-conversion so that this vision of cryogen free optical refrigeration can eventually be realized.

Research in the Kuno group is intrinsically interdisciplinary and spans areas such as physical chemistry/chemical physics, materials chemistry, inorganic chemistry, and even device chemistry/physics.

Selected Publications

• Biondelli, L.; Podshivaylov, E.; Ding, Y.; Stradley, W.; Filippi, U.; Frantsuzov, P. and Kuno, M. "Influence of the Local Environment on Mid-Infrared Photothermal Contrast" 2026 Nanoscale Horizons, in press. DOI: 10.1039/d5nh00801h.
• Moon, K.; Ding, Y.; Okrepka, H.; Wu, R. H.; Ewald, C. N.; Yadav, P.; Biswas, A.; Harel, E.; Kuno, M. and Kim, S. "Dynamic Behavior of Bound Interlayer Excitons in Interlayer-Doped Cs₃Bi₂Br₉ Vacancy-Ordered Perovskite" 2025 ACS Nano, 19 (42), pp.37398–37406. DOI: 10.1021/acsnano.5c14651.
• Szabó, G.; Kuno, M. and Kamat, P. V. "Iodine's Wild Ride Leading to Photoinstability in Halide Perovskite Solar Cells" 2025 ACS Energy Letters, 10 (9), pp.4378–4385. DOI: 10.1021/acsenergylett.5c02199.
• Favaro, M.; Eichhorn, J.; Kuno, M. and Subramanian, V. R. "An Interdisciplinary Perspective to the Application of in Situ/Operando Techniques in Photocatalytic and Electrocatalytic Processes and its Future" 2025 ChemPhysChem, 26 (15), e202401148. DOI: 10.1002/cphc.202401148.
• Zhang, Z. M.; Ding, Y.; Pauzauskie, P. J.; Sheik-Bahae, M.; Seletskiy, D. V. and Kuno, M. "Principles for Demonstrating Condensed Phase Optical Refrigeration" 2025 Nature Reviews Physics, 7 (3), pp.149–153. DOI: 10.1038/s42254-024-00804-2.
• Okrepka, H.; Franzini, L.; Pagliara, S. and Kuno, M. "Photoremixing of Photosegregated Formamidinium/Cesium Lead Iodide/Bromide Thin Films Under Pulsed Laser Excitation" 2024 ACS Energy Letters, 9 (12), pp.5744–5746. DOI: 10.1021/acsenergylett.4c02582.