Carbon Nitride with Rationally Designed π-Conjugated Structure for Bright Blue-Violet Light-Emitting Diodes

作者：He, Xingchen; Meng, Lingqiang; Liu, Yanliang; Zhang, Xue; Cheng, Ziqiang; Huang, Hao; He, Rui; Pan, Hao; Kang, Yihong; Li, Jia; Wang, Yiqing; Chu, Paul K.; Xu, Baomin; Wang, Jiahong^*; Yu, Xue-Feng^*

来源：Small, 2022, 18(31): 2202969.

DOI：10.1002/smll.202202969

• blue-violet light emission
• carbon nitride
• light emitting diodes
• 2D materials
• pi-conjugated structure

Carbon nitride consisting of the broken pi-conjugated structure (bc-CN) is designed as the emitting layer in a blue-violet light emitting diode (LED). The bc-CN is prepared by a metal-oxide (MgO) template-assisted method, in which the low reaction temperature and nano MgO jointly control the degree of polymerization to form cyano groups and broken pi-conjugation in the bc-CN nanosheets (bc-CN NS) which emit intense blue-violet photoluminescence at 412 nm. The broken pi-conjugated heptazine-ring structure in the bc-CN NS mitigates non-radiation energy loss and promotes the delta*-LP transition. As a result, a high quantum efficiency of 73.1% is achieved. The excellent dispersing ability of the bc-CN NS enables solution-based fabrication of the light emitting diode (LED). The LED exhibits intense electroluminescence of 236 cd m(-2) at 412 nm with an external quantum efficiency of 0.46%. The broken pi-conjugation modulates the optical properties of the polymerized carbon nitride semiconductor giving rise to intense blue-violet electroluminescence, which is very desirable for printable and wide-color-gamut display devices.

• 单位
  中国科学院; 南京大学