Recent progress of green thermally activated delayed fluorescent emitters

Abstract

Pure organic-based thermally activated delayed fluorescent (TADF) emitters have been studied for the last five years because of their potential as high-efficiency emitters comparable to phosphorescent emitters. Although the initial external quantum efficiency (EQE) of the TADF emitters was much lower than that of phosphorescent emitters, the current EQE of the TADF organic light-emitting diodes (OLEDs) is quite similar to that of phosphorescent OLEDs. In particular, the EQE of the green TADF OLEDs is already over 30% with the help of the new molecular design fully harvesting triplet excitons of the TADF emitters for light emission through the up-conversion process. In this work, the progress of the device performances of the TADF OLEDs was studied by reviewing the green TADF emitters that had been developed in the last five years. ARTICLE HISTORY

Rational Molecular Design Overcoming the Long Delayed Fluorescence Lifetime and Serious Efficiency Roll‐Off in Blue Thermally Activated Delayed Fluorescent Devices

“…[1][2][3][4][5][6][7] Instead of Ir-based organometallic emitters, pure organic-based TADF emitters are used in TADF devices,w hich is advantageous in terms of molecular-design versatility and low material cost. [8][9][10][11] However, the device performance of TADF OLEDsi si nferior to that of phosphorescent OLEDs,and further study is required.…”

The suppression of viewing angle dependence of top emission organic light emitting diodes having strong microcavity characteristics by applying concave patterned anode

“…The organic light emitting diodes (OLEDs) are rapidly applied in mobile display applications because of their high contrast ratio, vivid color, rapid response time, slim and flexible design form factor, etc . In particular, because mobile products are requiring low power consumption to realize long battery life time, the efficiency of OLED is a very significant study theme.…”

“…The organic light emitting diodes (OLEDs) are rapidly applied in mobile display applications because of their high contrast ratio, vivid color, rapid response time, slim and flexible design form factor, etc. [1][2][3][4] In particular, because mobile products are requiring low power consumption to realize long battery life time, the efficiency of OLED is a very significant study theme. Thus, many research groups and display panel manufactures have studied the outcoupling enhancement of OLEDs for the last decades to obtain highly power efficient devices because the maximum outcoupling efficiency of typical OLEDs without using such technologies is not more than 20%, although internal quantum efficiency of OLEDs themselves is almost 100% because the light loss is inevitably occurred by the total internal reflection and/or surface plasmon coupling, absorption, etc.…”

Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices

“…[11][12][13] Recently, thermally activated delayed fluorescence (TADF) emitters based on pure organic compounds have been considered as an alternate technology to phosphorescent counterparts to realize an IQE of 100%. [14][15][16][17][18][19][20][21][22][23][24][25] Until recently, several TADF OLEDs have achieved a high EQE of over 30% at maximum. [26][27][28][29][30][31][32] The efficiency of the TADF-based OLEDs is expected to exceed that of OLEDs based on phosphorescent emitters due to the unlimited molecular design of pyrimidine derivative-based TADF emitters.…”