G Grinblat, I Abdelwahab, M P Nielsen, P Dichtl, K Leng, R F Oulton, K P Loh, S A Maier Ultrafast All-Optical Modulation in 2D Hybrid Perovskites Journal Article ACS Nano, 13 (8), pp. 9504-9510, 2019, ISSN: 1936-0851. Links | Tags: Solid-Solid @article{, title = {Ultrafast All-Optical Modulation in 2D Hybrid Perovskites}, author = {G Grinblat and I Abdelwahab and M P Nielsen and P Dichtl and K Leng and R F Oulton and K P Loh and S A Maier}, url = {https://doi.org/10.1021/acsnano.9b04483}, doi = {10.1021/acsnano.9b04483}, issn = {1936-0851}, year = {2019}, date = {2019-08-27}, journal = {ACS Nano}, volume = {13}, number = {8}, pages = {9504-9510}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } |
L Polavarapu, H Huang, Y Li, Y Tong, E-P Yao, M Döblinger, M W Feil, A F Richter, A L Rogach, J Feldmann Spontaneous Crystallization of Perovskite Nanocrystals in Nonpolar Organic Solvents: A Versatile Approach for their Shape-controlled Synthesis Journal Article Angewandte Chemie International Edition, 0 (ja), 2019, ISSN: 1433-7851. Abstract | Links | Tags: Solid-Solid @article{, title = {Spontaneous Crystallization of Perovskite Nanocrystals in Nonpolar Organic Solvents: A Versatile Approach for their Shape-controlled Synthesis}, author = {L Polavarapu and H Huang and Y Li and Y Tong and E-P Yao and M D\"{o}blinger and M W Feil and A F Richter and A L Rogach and J Feldmann}, url = {https://doi.org/10.1002/anie.201906862}, doi = {10.1002/anie.201906862}, issn = {1433-7851}, year = {2019}, date = {2019-08-21}, journal = {Angewandte Chemie International Edition}, volume = {0}, number = {ja}, abstract = {The growing demand of perovskite nanocrystals (NCs) for various applications has stimulated great research interest in the development of facile synthetic methods. They have often been synthesized by either ligand assisted reprecipitation (LARP) at room temperature or by hot-injection at high temperatures and inert atmosphere. However, the use of polar solvents in LARP effects their stability. Herein, we report on the spontaneous crystallization of perovskite nanocrystals in nonpolar organic media at ambient conditions by simple mixing of precursor-ligand complexes without applying any external stimuli. The shape of the NCs can be controlled from nanocubes to nanoplatelets by varying the ratio of monovalent (e.g. formamidinium+ (FA+) and Cs+) to divalent (Pb2+) cation-ligand complexes. The precursor-ligand complexes are stable for months, and thus perovskite NCs can be readily prepared prior to use. Moreover, we show that this versatile synthetic process is scalable and can be generally applicable for perovskite NCs of different compositions.}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } The growing demand of perovskite nanocrystals (NCs) for various applications has stimulated great research interest in the development of facile synthetic methods. They have often been synthesized by either ligand assisted reprecipitation (LARP) at room temperature or by hot-injection at high temperatures and inert atmosphere. However, the use of polar solvents in LARP effects their stability. Herein, we report on the spontaneous crystallization of perovskite nanocrystals in nonpolar organic media at ambient conditions by simple mixing of precursor-ligand complexes without applying any external stimuli. The shape of the NCs can be controlled from nanocubes to nanoplatelets by varying the ratio of monovalent (e.g. formamidinium+ (FA+) and Cs+) to divalent (Pb2+) cation-ligand complexes. The precursor-ligand complexes are stable for months, and thus perovskite NCs can be readily prepared prior to use. Moreover, we show that this versatile synthetic process is scalable and can be generally applicable for perovskite NCs of different compositions. |
S D Gennaro, Y Li, S A Maier, R F Oulton Nonlinear Pancharatnam−Berry Phase Metasurfaces beyond the Dipole Approximation Journal Article ACS Photonics, 2019. Links | Tags: Solid-Solid @article{, title = {Nonlinear Pancharatnam−Berry Phase Metasurfaces beyond the Dipole Approximation}, author = {S D Gennaro and Y Li and S A Maier and R F Oulton}, url = {https://doi.org/10.1021/acsphotonics.9b00877}, doi = {10.1021/acsphotonics.9b00877}, year = {2019}, date = {2019-08-12}, journal = {ACS Photonics}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } |
E Pensa, J Gargiulo, A Lauri, S Schlücker, E Cortés, S A Maier Spectral Screening of the Energy of Hot Holes over a Particle Plasmon Resonance Journal Article Nano Letters, 19 (3), pp. 1867-1874, 2019, ISSN: 1530-6984. Links | Tags: Solid-Solid @article{, title = {Spectral Screening of the Energy of Hot Holes over a Particle Plasmon Resonance}, author = {E Pensa and J Gargiulo and A Lauri and S Schl\"{u}cker and E Cort\'{e}s and S A Maier}, url = {https://doi.org/10.1021/acs.nanolett.8b04950}, doi = {10.1021/acs.nanolett.8b04950}, issn = {1530-6984}, year = {2019}, date = {2019-03-13}, journal = {Nano Letters}, volume = {19}, number = {3}, pages = {1867-1874}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } |
B Doiron, M Mota, M P Wells, R Bower, A Mihai, Y Li, L F Cohen, N M Alford, P K Petrov, R F Oulton, S A Maier Quantifying Figures of Merit for Localized Surface Plasmon Resonance Applications: A Materials Survey Journal Article ACS Photonics, 6 (2), pp. 240-259, 2019. Links | Tags: Solid-Solid @article{, title = {Quantifying Figures of Merit for Localized Surface Plasmon Resonance Applications: A Materials Survey}, author = {B Doiron and M Mota and M P Wells and R Bower and A Mihai and Y Li and L F Cohen and N M Alford and P K Petrov and R F Oulton and S A Maier}, url = {https://doi.org/10.1021/acsphotonics.8b01369}, doi = {10.1021/acsphotonics.8b01369}, year = {2019}, date = {2019-02-20}, journal = {ACS Photonics}, volume = {6}, number = {2}, pages = {240-259}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } |
B Miller, J Lindlau, M Bommert, A Neumann, H Yamaguchi, A W Holleitner, A Högele, U Wurstbauer Tuning the Fröhlich exciton-phonon scattering in monolayer MoS2 Journal Article Nature Communications, 10 (1), pp. 807, 2019, ISSN: 2041-1723. Abstract | Links | Tags: Solid-Solid @article{, title = {Tuning the Fr\"{o}hlich exciton-phonon scattering in monolayer MoS2}, author = {B Miller and J Lindlau and M Bommert and A Neumann and H Yamaguchi and A W Holleitner and A H\"{o}gele and U Wurstbauer}, url = {https://doi.org/10.1038/s41467-019-08764-3}, doi = {10.1038/s41467-019-08764-3}, issn = {2041-1723}, year = {2019}, date = {2019-02-18}, journal = {Nature Communications}, volume = {10}, number = {1}, pages = {807}, abstract = {Charge carriers in semiconducting transition metal dichalcogenides possess a valley degree of freedom that allows for optoelectronic applications based on the momentum of excitons. At elevated temperatures, scattering by phonons limits valley polarization, making a detailed knowledge about strength and nature of the interaction of excitons with phonons essential. In this work, we directly access exciton-phonon coupling in charge tunable single layer MoS2 devices by polarization resolved Raman spectroscopy. We observe a strong defect mediated coupling between the long-range oscillating electric field induced by the longitudinal optical phonon in the dipolar medium and the exciton. This so-called Fr\"{o}hlich exciton phonon interaction is suppressed by doping. The suppression correlates with a distinct increase of the degree of valley polarization up to 20% even at elevated temperatures of 220 K. Our result demonstrates a promising strategy to increase the degree of valley polarization towards room temperature valleytronic applications.}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } Charge carriers in semiconducting transition metal dichalcogenides possess a valley degree of freedom that allows for optoelectronic applications based on the momentum of excitons. At elevated temperatures, scattering by phonons limits valley polarization, making a detailed knowledge about strength and nature of the interaction of excitons with phonons essential. In this work, we directly access exciton-phonon coupling in charge tunable single layer MoS2 devices by polarization resolved Raman spectroscopy. We observe a strong defect mediated coupling between the long-range oscillating electric field induced by the longitudinal optical phonon in the dipolar medium and the exciton. This so-called Fröhlich exciton phonon interaction is suppressed by doping. The suppression correlates with a distinct increase of the degree of valley polarization up to 20% even at elevated temperatures of 220 K. Our result demonstrates a promising strategy to increase the degree of valley polarization towards room temperature valleytronic applications. |
E-P Yao, B J Bohn, Y Tong, H Huang, L Polavarapu, J Feldmann Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal–Fullerene Composites: Layer-by-Layer versus Blend Structures Journal Article Advanced Optical Materials, 7 (8), pp. 1801776, 2019, ISSN: 2195-1071. Abstract | Links | Tags: Solid-Solid @article{, title = {Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal\textendashFullerene Composites: Layer-by-Layer versus Blend Structures}, author = {E-P Yao and B J Bohn and Y Tong and H Huang and L Polavarapu and J Feldmann}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201801776}, doi = {10.1002/adom.201801776}, issn = {2195-1071}, year = {2019}, date = {2019-02-18}, journal = {Advanced Optical Materials}, volume = {7}, number = {8}, pages = {1801776}, abstract = {Abstract Solution-processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin-film counterparts. However, the charge transfer dynamics in perovskite NC based light-harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer-by-layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer-by-layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure-based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron- or hole-transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection.}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } Abstract Solution-processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin-film counterparts. However, the charge transfer dynamics in perovskite NC based light-harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer-by-layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer-by-layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure-based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron- or hole-transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection. |
T Wu, Y Luo, S A Maier, L Wei Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler Journal Article Physical Review Applied, 11 (1), pp. 014049, 2019, (PRAPPLIED). Abstract | Links | Tags: Solid-Solid @article{, title = {Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler}, author = {T Wu and Y Luo and S A Maier and L Wei}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.11.014049}, doi = {10.1103/PhysRevApplied.11.014049}, year = {2019}, date = {2019-01-24}, journal = {Physical Review Applied}, volume = {11}, number = {1}, pages = {014049}, abstract = {Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies.}, note = {PRAPPLIED}, keywords = {Solid-Solid}, pubstate = {published}, tppubtype = {article} } Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies. |
PublicationsPeter Sonntag2020-02-06T17:19:45+01:00