Phase transition induced spectral tuning of dual luminescent crystalline zinc-phthalocyanine thin films and OLEDs

Abstract

We analyze the impact of the first order structural phase transition between the α- and β-phases in crystalline zinc-phthalocyanine thin films on their luminescent behavior. Upon optical excitation, two intensity maxima governing the dual fluorescence can be attributed to thin film excimer emission of the α-phase at 930 nm and bulk Frenkel exciton emission of the corresponding β-phase at 780 nm. Comprehensive temperature and time dependent studies on the structural phase transition reveal a controllable shift of spectral weight between these two maxima. Applying this approach to thin film devices, we demonstrate the preparation of dual luminescent organic light emitting diodes with tunable emission characteristics in the near infrared, which are of interest as electro-optical units in future hybrid photonic devices.

Strong Photophysical Diversity and the Role of Charge Transfer Excitons in Transition Metal Phthalocyanine β-Phases

“…Our PL data for β-ZnPc and β-CuPc agree well in energy and spectral shape with what has been published previously. , Also, it has been mentioned that for β-NiPc crystals no PL signal could be observed …”

“…Our PL data for β-ZnPc and β-CuPc agree well in energy and spectral shape with what has been published previously. 35,36 Also, it has been mentioned that for β-NiPc crystals no PL signal could be observed. 35 Thus, while ZnPc, CuPc and NiPc show virtually identical absorption and emission spectra in isolated molecular state, the optical absorption in the β-phase is visibly different, and the PL emission differs tremendously.…”

Vibrationally resolved absorption spectra and ultrafast exciton dynamics in α-phase and β-phase zinc phthalocyanine aggregates

“…Both α-phase and β-phase ZnPc have significant differences in their optical properties. 8,12,14,24–27 For instance, it has been shown that during the α-to-β phase-transition process, the absorbance of the thin film from the ultraviolet to the near-infrared regions can be enlarged by 1.5 to 2 times, which has been attributed to the increment in the angle between the molecular plane and the incident direction of the light. 27 In addition, both phases exhibit two absorption peaks in the Q-band region, but along with the phase transition, it is remarkable that the relative intensities of the two peaks are reversed.…”

Fabrication of (Au, Mn)/ZnPc/Ag Interfaces as Radiowave/Microwave Band Filters

“…It is nominated as tunable dual luminescent organic light‐emitting diodes. [ 1 ] ZnPc and its derivatives are also used as ambipolar devices. [ 2 ] These devices display a current on/off ratio of 10 5 .…”