2, 6‐Dicarbonitrile Diphenyl‐1λ5‐Phosphinine (DCNP)—A Robust Conjugated Building Block for Multi‐Functional Dyes Exhibiting Tunable Amplified Spontaneous Emission. Issue 21 (2nd September 2021)

• Record Type: Journal Article
• Authors: Balijapalli, Umamahesh; Tang, Xun; Okada, Daichi; Lee, Yi‐Ting; Karunathilaka, Buddhika S. B.; Auffray, Morgan; Tumen‐Ulzii, Ganbaatar; Tsuchiya, Youichi; Sandanayaka, Atula S. D.; Matsushima, Toshinori; Nakanotani, Hajime; Adachi, Chihaya
• Is Part Of: Advanced optical materials. Volume 9:Issue 21(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-02
• Subjects: amplified spontaneous emission -- external electroluminescence quantum efficiency -- organic light‐emitting diodes -- TADF‐assistant fluorescence -- thermally‐activated delayed fluorescence; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.202101122
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Highly efficient organic light‐emitting diodes (OLEDs) with the concurrent achievement of high external electroluminescence quantum efficiency (EQE) and low light amplification thresholds under optical excitation have been considered as a crucial evolution towards the development of high‐performance electrically pumped organic semiconductor laser diodes. Herein, a series of 2, 6‐dicarbonitrile‐diphenyl‐1λ 5 ‐phosphinine (DCNP ) based donor (D)‐acceptor (A) type dyes with different electron‐withdrawing and donating moieties have been designed and characterized. The well‐manipulated D‐A strength with tunable optical properties guaranteed the low amplified spontaneous emission (ASE) thresholds of below 10 µJ cm −2 and furnished a wide‐range color‐tuning capability in the visible region (485–595 nm). Furthermore, employing a thermally‐activated delayed fluorescence (TADF) molecule as a triplet harvester boosted the performance of OLEDs based on m DMCz that exhibits an exceptional EQE value of 18.4% which is an eightfold enhancement as compared with that of standard fluorescence OLEDs. Also, the TADF‐assistant fluorescence (TAF) system enables a reduction of the ASE threshold to 3 µJ cm −2 and excellent ASE stability. These results provide a rational design strategy to construct color‐tunable lasing dyes with reduced ASE thresholds and clarify their potentiality as the fluorescent dopant in the TAF system to utilize up‐converted triplet excitons via efficient energy transfer. Abstract : Wide‐range color tunable 2, 6‐dicarbonitrile‐diphenyl‐1λ 5 ‐phosphinine (DCNP) based dyes are easily synthesized, which exhibit amplified spontaneous emission (ASE) thresholds below 10 µJ cm −2 . The TADF‐assistant fluorescence (TAF) system exhibits superior electroluminescence performance with an exceptional external quantum efficiency of 18.4%, a reduction of the ASE threshold to 3 µJ cm −2 and excellent ASE stability.