▎ 摘　　要

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 (beta(0)) up to 2.5 x 10(6) a.u. (22000 x 10(-30) esu) for H2N-(7,3)ZGNR-NO2 (ZGNR=zigzag-edged GNR), which is about 15 times larger than the recorded value of beta(0) (1470 x 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 beta(0) 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.