A series of homoleptic bis(phthalocyaninato) rare earth sandwich complexes with large two-photon absorption cross-section

• The 2PA properties of a series of sandwich type complexes were investigated.
• All complexes exhibit large 2PA cross-sections.
• The unique π–π interaction in these complexes is effective to improve their 2PA properties.

The third-order nonlinear optical properties of a series of homoleptic substituted phthalocyaninato rare earth double-decker complexes were experimentally investigated by the Z-scan technique at the wavelength of 800 nm. All complexes were revealed to exhibit large two-photon absorption cross-sections. The measured two-photon absorption values of these complexes remain constant at different laser intensities, indicating nonlinearity is originated from pure two-photon absorption behavior. In addition, the two-photon absorption cross-section of these complexes increases along with the decrease of the rare earth atomic radius, suggesting that intense intramolecular π–π interaction between the phthalocyaninato macrocycles improves the third-order nonlinear optical properties. The optical limiting behavior of these complexes in chloroform was also investigated by using femtosecond laser pulses. The excellent two-photon absorption properties and optical limiting performance indicate their good application potential in photonic and optoelectronic devices.