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Multipolar symmetric squaraines with large two-photon absorption cross-sections in the NIR region
E Collini1, S Carlotto, C Ferrante
1Department of Chemical Sciences and UdR INSTM, University of Padova, Via Marzolo 1, I-35131 Padova, Italy.
Physical Chemistry Chemical Physics : PCCP
|June 1, 2011
Summary
Two novel squaraine dyes exhibit exceptionally high two-photon absorption (TPA) cross sections. Quantum chemical calculations reveal that a peripheral group enhances TPA properties, setting a new record for this molecular class.
Area of Science:
- Materials Science
- Photochemistry
- Computational Chemistry
Background:
- Squaraine dyes are known for their optical properties.
- Tuning molecular architecture is crucial for enhancing photophysical characteristics.
Purpose of the Study:
- To characterize the two-photon absorption (TPA) properties of two novel extended symmetric squaraine dyes.
- To elucidate the origin of their high TPA cross sections through experimental and computational methods.
Main Methods:
- Experimental characterization using the Z-scan technique in the femtosecond regime.
- Quantum-chemical calculations including CIS and TDDFT methods.
- Analysis of molecular structure-property relationships.
Main Results:
- Both squaraine dyes demonstrated significantly high TPA cross sections (σ(TPA)).
- The squaraine with a more extended A'-π-D-π-A-π-D-π-A' structure achieved the highest reported σ(TPA) for this class.
- Computational results correlated well with experimental data.
Conclusions:
- The enhanced TPA properties are attributed to the molecular design, specifically the inclusion of a peripheral A' group.
- This peripheral group increases the density of excited states contributing to the TPA process.
- The findings pave the way for developing advanced materials with superior TPA capabilities.
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