Ultrafast Dynamics Surface Enhanced Fluorescence Through Plasmonic Nanoclusters

In this work, Perovskite nanowires (NWs) are synthesized and encapsulated by gold nanoparticle clusters in polymer matrix to construct a random medium, which allows surface plasmons of the metal nanoclusters to be confined in subwavelength regions and causes an extreme electromagnetic field concentration to manipulate the fluorescence dynamics of the interacting quantum sources. The strong plasmonic field of the gold nanocluster induces a dramatic enhancement in the Purcell factor (>10⁴). When the Purcell factor exceeds 10⁴ through the intense light confinement based on plasmonic nanoclusters, the ultrafast dynamics surface enhanced fluorescence (UFDSEF) of the light emitters exists to dramatically modify the characteristic properties of the quantum sources. As the internal relaxation rate of the Perovskite quantum sources in a bare polymer is greatly faster than the total decay rate, on the excitation of the plasmonic nanocluster, which surrounds the fluorescent emitters in polymer matrix, the strong electromagnetic field enhances the population rates of the excited states; thus, electrons emit from higher vibrational excited states to the ground states. Then, the total decay rate becomes comparable to the internal relaxation rate, which results in significant changes in the spectral profiles of the quantum emitters. The fluorescence emission signal of the quantum sources surrounded by the plasmonic nanocluster seems to be shifted to the wavelength of 476 nm as the peak wavelength in photoluminescence spectrum of the semiconductor NWs in bare polymer appears at 526 nm. Thus, our photonic design proposed in this work, which consists of semiconductor nanocrystals and plasmonic nanoclusters in polymer matrix, provides a distinctive basis to explore the fluorescence dynamics of the quantum sources through UFDSEF mechanism. The first exploration of the blueshifted photoluminescence signal of the Perovskite NWs is achieved by plasmon-induced intense light−matter interaction. The concept of light concentration in deep subwavelength regions of the random medium provides a significant potential to explore light−matter interaction in photonic-plasmonic environment and to develop highly efficient light-emitting device applications.