Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter

Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100 K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process.

[1]  Martin R. Bryce,et al.  Triplet Harvesting with 100% Efficiency by Way of Thermally Activated Delayed Fluorescence in Charge Transfer OLED Emitters , 2013, Advanced materials.

[2]  T. Imato,et al.  Solvent effect on thermally activated delayed fluorescence by 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene. , 2013, The journal of physical chemistry. A.

[3]  J. Kalinowski,et al.  Phosphorescence response to excitonic interactions in Ir organic complex-based electrophosphorescent emitters , 2005 .

[4]  S. Forrest,et al.  Nearly 100% internal phosphorescence efficiency in an organic light emitting device , 2001 .

[5]  Edwin K. P. Chong,et al.  An Introduction to Optimization: Chong/An Introduction , 2008 .

[6]  C. Adachi,et al.  Highly efficient organic light-emitting diodes by delayed fluorescence , 2013 .

[7]  Chihaya Adachi,et al.  Analysis of exciton annihilation in high-efficiency sky-blue organic light-emitting diodes with thermally activated delayed fluorescence , 2013 .

[8]  Ken-Tsung Wong,et al.  Enhanced electroluminescence based on thermally activated delayed fluorescence from a carbazole-triazine derivative. , 2013, Physical chemistry chemical physics : PCCP.

[9]  Karl Leo,et al.  Organic light-emitting diodes under high currents explored by transient electroluminescence on the nanosecond scale , 2011 .

[10]  S. Forrest,et al.  Highly efficient phosphorescent emission from organic electroluminescent devices , 1998, Nature.

[11]  C. Adachi,et al.  Highly Efficient Organic Light‐Emitting Diode Based on a Hidden Thermally Activated Delayed Fluorescence Channel in a Heptazine Derivative , 2013, Advanced materials.

[12]  Stephen R. Forrest,et al.  Transient analysis of organic electrophosphorescence: I. Transient analysis of triplet energy transfer , 2000 .

[13]  Tukaram K. Hatwar,et al.  Triplet annihilation exceeding spin statistical limit in highly efficient fluorescent organic light-emitting diodes , 2009 .

[14]  Daisuke Yokoyama,et al.  Thermally Activated Delayed Fluorescence from Sn4+–Porphyrin Complexes and Their Application to Organic Light Emitting Diodes — A Novel Mechanism for Electroluminescence , 2009, Advanced materials.

[15]  A. Monkman,et al.  The contribution of triplet–triplet annihilation to the lifetime and efficiency of fluorescent polymer organic light emitting diodes , 2011 .

[16]  H. Naito,et al.  Temperature Dependence of Photoluminescence Lifetime and Quantum Efficiency in Neat fac-Ir(ppy)3 Thin Films , 2005 .

[17]  S. Forrest,et al.  Triplets contribute to both an increase and loss in fluorescent yield in organic light emitting diodes. , 2012, Physical review letters.

[18]  J. Kalinowski,et al.  Unified approach to electroluminescence efficiency in organic light-emitting diodes , 2010 .