Unexpected discovery that molecules of organic dyes when they form regular structures can change dramatically their light absorption and fluorescence properties were attracting the minds of researchers for more than eight decades. The progress in investigation of this unique phenomenon described in terms of H- and J-aggregation has led to many practical applications. Here the author expresses his personal view on the dramatic story of switching this research area from empirical knowledge to that standing on strong background of molecular exciton theory. The author was a witness of some of these events and acquainted with several great personalities involved. The major trends of future developments are highlighted.
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http://dx.doi.org/10.1002/tcr.202300290 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Jiangnan University, International Joint Research Laboratory for Biointerface and Biodetection, lihu road 1800#, 214122, Wuxi, CHINA.
Circularly polarized luminescence (CPL) has garnered significant research attention. Achieving a high luminescence dissymmetry factor (glum) is a key challenge in this field. Herein, we reported, for the first time, the fabrication of a chiral assembled film consisting of chiral D-/L-Selenium nanoparticles (D-/L-Se NPs) and DSPE-PEG-NH2 modified upconversion nanoparticles (DPNUCNPs) with remarkable CPL properties that were generated by the interfacial self-assembly technique.
View Article and Find Full Text PDFACS Nano
December 2024
Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Collective optical properties can emerge from an ordered ensemble of emitters due to interactions between the individual units. Superlattices of halide perovskite nanocrystals exhibit collective light emission, influenced by dipole-dipole interactions between simultaneously excited nanocrystals. This coupling changes both the emission energy and rate compared to the emission of uncoupled nanocrystals.
View Article and Find Full Text PDFJ Phys Condens Matter
December 2024
Department of Physics, Indian Institute of Technology Delhi, IIT Delhi, Hauz Khas, New Delhi, Delhi, 110016, INDIA.
We have grown (111)- and (001)-oriented NiO thin films on (0001)-Sapphire and (001)-MgO substrates using pulsed laser deposition (PLD), respectively. DC magnetic susceptibility measurements underline that the Néel temperatures of the samples are beyond room-temperature. This is further confirmed by the presence of two-magnon Raman scattering modes in these films in ambient conditions.
View Article and Find Full Text PDFIn doped semiconductors such as monolayer transition-metal dichalcogenides (TMDs), the optical properties are predominantly determined by exciton polarons, which are coherent superpositions of excitons and electron-hole excitation pairs in the Fermi sea. Here, we theoretically study the effect of exciton polarons on thermal radiation in doped two-dimensional semiconductors. By deriving an emissivity formula in terms of the dielectric function and the thickness of two-dimensional semiconductors, we show that the emissivity spectrum exhibits a narrow peak at the energy of an exciton polaron.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Center on Nanoenergy Research, Carbon Peak and Neutrality Science and Technology Development Institute, School of Physical Science & Technology, Guangxi University, Nanning, 530004, China.
Nonfullerene acceptors are critical in advancing the performance of organic solar cells. However, unfavorable morphology and low photon-to-electron conversion in the acceptor range continue to limit the photocurrent generation and overall device performance. Herein, benzoic anhydride, a low-cost polar molecule with excellent synergistic properties, is introduced in combination with the traditional additive 1-chloronaphthalene to optimize the aggregation of nonfullerene acceptors.
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