Abstract
A new design of peculiar-shaped β-NaYF4: 20% Yb3+/2% Er3+ hexagonal microcrystal (PSβHM) is proposed and its upconversion (UC) luminescence with adjustable color pattern is studied with near infrared excitation. Flower-like green UC luminescence emission pattern from blooming to withering process and intensive directional red emission are achieved by simply adjusting the focal point position of the excitation light. The mechanism that determines the unique UC luminescence phenomena are investigated systematically. The function of the internal light reflection and waveguide effect with annular microcavity is explored based on the structure characteristic of the hexagonal microplate. The current work may have great significant and potential applications in the development of optoelectronic device, color display, directional light and laser emission of microsystem.
Highlights
Lanthanide-doped upconversion (UC) is a multiphoton processes that is characterized by simultaneous or successive absorption of two or more low-energy photons via intermediate energy states, followed by a high-energy photon emission[1]
We present a novel UC emission of peculiar-shaped β-NaYF4: 20% Yb3+/2% Er3+ single microcrystal (PSβHM) with unique morphology
A newly designed peculiar-shaped β-NaYF4: 20% Yb3+/2% Er3+ hexagonal microcrystal (PSβHM) is synthesized and unique UC emissions with adjustable flower-like pattern and directional radiation are reported for the first time
Summary
Lanthanide-doped upconversion (UC) is a multiphoton processes that is characterized by simultaneous or successive absorption of two or more low-energy photons via intermediate energy states, followed by a high-energy photon emission[1]. Unique optical properties including high signal to noise ratio, large anti-stokes shift, high photochemical stability and low toxicity, are typical for lanthanide doped luminescence materials[4, 5]. These characteristics make lanthanide-doped UC luminescence materials very attractive in fundamental research and practical oriented applications including solar cell[6], biological imaging7, 3D display[8], optical storage[9] and photo switching[10]. Light emission produced by dopant lanthanide could propagate along certain direction of the host material, directional UC emission should be obtained with fixed color gamut and pattern by controlling the composition of lanthanide dopant in microcrystal, the configuration of the particle morphology as well as the excitation condition[22]. The possible mechanism and UC luminescence from multiple connected PSβHM is proposed
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