| Title |
Thermally stable and energy efficient newly synthesized bipolar emitters for yellow and green OLED devices |
| Authors |
Kumar, Anil ; Lenka, Sushanta ; Patidar, Kapil ; Tung, Chih-An ; Luo, Ming Yu ; Beresneviciute, Raminta ; Krucaite, Gintare ; Tavgeniene, Daiva ; Blazevicius, Dovydas ; Blazeviciute, Bernadeta ; Jou, Jwo-Huei ; Grigalevicius, Saulius |
| DOI |
10.3390/molecules31010158 |
| Full Text |
|
| Is Part of |
Molecules.. Basel : MDPI. 2026, vol. 31, iss. 1, art. no. 158, p. 1-17.. ISSN 1420-3049 |
| Keywords [eng] |
bipolar emitter ; thermal stability ; glass transition temperature ; organic lightemitting diode ; efficiency ; photo-therapeutic |
| Abstract [eng] |
Organic light-emitting diodes (OLEDs) have emerged as a leading high-resolution display and lighting technology, as well as for photo-therapeutic applications, due to their light weight, flexibility, and excellent color rendering. However, achieving long-term thermal stability and high energy efficiency remains a principal issue for their widespread adoption. Strong thermal robustness in OLED emitter materials is a critical parameter for achieving long device lifetimes, stable film morphology, reliable high-temperature processing, and sustained interface integrity in high-performance hosts. Bipolar emitters RB14 (N-(9-ethylcarbazole-3-yl)-4-(diphenylamino)phenyl-9H-carbazole-9-yl-1,8-naphthalimide), RB18 (N-phenyl-4-(diphenylamino)phenyl-9H-carbazole-9-yl-1,8-naphthalimide), and RB22 (N-phenyl-3-(2-methoxypyridin-3-yl)-9H-carbazole-9-yl-1,8-naphthalimide) were newly synthesized. RB18 is a yellow bipolar OLED emitter that has a glass transition temperature (Tg) of 162 °C and thermal durability (Td) of 431 °C, which is the highest reported value for naphthalimide-based bipolar emitter derivatives for yellow OLEDs. Meanwhile, RB14 and RB22 are green OLED emitters that have glass transition temperatures (Tg) of 133 °C and 167 °C, and thermal durabilities (Td) of 336 °C and 400 °C, respectively. We have fabricated OLED devices using these bipolar emitters dispersed in CBP host matrix, and we have found that the maximum EQEs (%) for RB14, RB18, and RB22 emitter-based devices are 7.93%, 3.40%, and 4.02%, respectively. For confirmation of thermal stability, we also used UV-visible spectroscopy measurements at variable temperatures on annealed spin-coated glass films of these emitter materials and found that RB22 is the most thermally stable emitter among these materials. |
| Published |
Basel : MDPI |
| Type |
Journal article |
| Language |
English |
| Publication date |
2026 |
| CC license |
|
