Abstract Two novel conjugated pyrene derivatives (C1 and C2) with D- π -A structures were synthesized to realize broadband reverse saturable absorption (RSA) under femtosecond laser excitation (ranging from 515… Click to show full abstract
Abstract Two novel conjugated pyrene derivatives (C1 and C2) with D- π -A structures were synthesized to realize broadband reverse saturable absorption (RSA) under femtosecond laser excitation (ranging from 515 to 700 nm) resulting from two-photon absorption (TPA) and TPA-induced excited-state absorption. Furthermore, these two derivatives showed RSA on the picosecond and nanosecond time regions (532 nm). Quantum chemical calculations indicated that two mechanisms for the HOMO-LUMO excitation of the two molecules exist simultaneously: intramolecular charge transfer (which is considered to trigger the nonlinear optical response) and π-π* transition. It was found that the π-π* transition localized in the pyrene group can contribute to the increase in the nonlinear absorption of pyrene derivatives. Femtosecond time-resolved transient absorption spectrum provided information on the dynamics of the locally excited singlet state (1LE) and the charge-transfer state (1CT) for both compounds. The results show that these pyrene derivatives are promising candidates for future optoelectronic and RSA applications.
               
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