Exceptionally Large Second-Order Nonlinear Optical Response in Donor-Graphene Nanoribbon-Acceptor Systems

• Published in: Chemistry : a European journal Vol. 17; no. 8; pp. 2414 - 2419
• Main Authors: Zhou, Zhong-Jun, Li, Xiao-Ping, Ma, Fang, Liu, Zhen-Bo, Li, Zhi-Ru, Huang, Xu-Ri, Sun, Chia-Chung
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 18.02.2011; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Bridges (structures); Chemistry; Design engineering; donor-acceptor systems; first hyperpolarizability; Graphene; nanoribbons; Nanostructure; nonlinear optics; Nonlinearity; Optical materials
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201001727

Graphene nanoribbon (GNR) has been used, for the first time, as an excellent conjugated bridge in a donor–conjugated bridge–acceptor (D–B–A) framework to design high‐performance second‐order nonlinear optical materials. Owing to the unique diradical planar conjugated bridge of GNR, D(NH2)–GNR–A(NO2) exhibits exceptionally large static first hyperpolarizability (β0) up to 2.5×106 a.u. (22000×10−30 esu) for H2N–(7,3)ZGNR–NO2 (ZGNR=zigzag‐edged GNR), which is about 15 times larger than the recorded value of β0 (1470×10−30 esu) for the D–A polyene reported by Blanchard‐Desce et al. [Chem. Eur. J. 1997, 3, 1091]. Interestingly, we have found that the size effect of GNR plays a key role in increasing β0 for the H2N–GNR–NO2 system, in which the width effect of GNR perpendicular to the D–A direction is superior to the length effect along the D–A direction. Bridging the gap: Graphene nanoribbons (GNRs), serving as excellent conjugated bridges, have been introduced into donor (D)–conjugated bridge–acceptor (A) frameworks for the first time to give high‐performance nonlinear optical (NLO) materials. D–GNR–A (in which D=NH2 and A=NO2; see figure) exhibits an exceptionally large static first hyperpolarizability.