To switch quadratic nonlinear optical（NLO） effects has become an exciting branch of the NLO material science. However, solid-state molecular crystals showing tunable and switchable NLO behaviors remain scarce. Here,...To switch quadratic nonlinear optical（NLO） effects has become an exciting branch of the NLO material science. However, solid-state molecular crystals showing tunable and switchable NLO behaviors remain scarce. Here, we report an organic picrate-based binary molecular crystal, triethylammonium picrate（TEAP）, which undergoes an above-room-temperature phase transition at T_c=319 K, being solidly confirmed by the thermal and dielectric measurements. A large thermal hysteresis of ~7 K discloses the first-order feature for its phase transition. More strikingly, the quadratic NLO effects of TEAP can be switched in the vicinity of Tc. That is, TEAP exhibits NLO-active response of ~1.5 times as large as that of KDP below T_c（i.e., NLO-on state）, while its NLO effects totally disappear above T_c（NLO-off state）. Structure analyses disclose that the order-disorder transformations of triethylammonium cations and picrate anions collectively contribute to its phase transition, as well as switchable NLO behaviors. This work opens up a new pathway to the designing and assembling of stimuli-responsive materials.展开更多
基金supported by the National Natural Science Foundation of China(Nos. 21622108, 21525104, 21601188, 91422301, 21373220, 51402296 and 51502290)the Natural Science Foundation of Fujian Province(No. 2015J05040)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(No. XDB20000000)the Youth Innovation Promotion of CAS(No. 2014262)the State Key Laboratory of Luminescence and Applications(No. SKLA-2016-09)
文摘To switch quadratic nonlinear optical（NLO） effects has become an exciting branch of the NLO material science. However, solid-state molecular crystals showing tunable and switchable NLO behaviors remain scarce. Here, we report an organic picrate-based binary molecular crystal, triethylammonium picrate（TEAP）, which undergoes an above-room-temperature phase transition at T_c=319 K, being solidly confirmed by the thermal and dielectric measurements. A large thermal hysteresis of ~7 K discloses the first-order feature for its phase transition. More strikingly, the quadratic NLO effects of TEAP can be switched in the vicinity of Tc. That is, TEAP exhibits NLO-active response of ~1.5 times as large as that of KDP below T_c（i.e., NLO-on state）, while its NLO effects totally disappear above T_c（NLO-off state）. Structure analyses disclose that the order-disorder transformations of triethylammonium cations and picrate anions collectively contribute to its phase transition, as well as switchable NLO behaviors. This work opens up a new pathway to the designing and assembling of stimuli-responsive materials.
