Anti-Stokes Emission Utilizing Reverse Intersystem Crossing

Area of Science:

• Organic electronics
• Photophysics
• Materials science

Background:

• Photon-upconversion (PUC) is key for energy harvesting, but efficient, loss-free methods are lacking.
• Existing PUC methods like triplet-triplet upconversion have limitations in yield and energy efficiency.

Purpose of the Study:

• To propose and investigate a novel PUC mechanism utilizing reverse intersystem crossing in thermally activated delayed fluorescence (TADF) molecules.
• To explore the potential of combining triplet sensitizers with TADF molecules for efficient energy transfer and anti-Stokes emission.

Main Methods:

• Investigated a PUC process involving a triplet sensitizer (Ir(ppy)3) and a TADF molecule (CzBSe).
• Analyzed triplet energy transfer dynamics and anti-Stokes emission characteristics.
• Studied the influence of triplet radiative decay rate and Gibbs energy difference on energy transfer efficiency.

Main Results:

• Demonstrated an alternative PUC mechanism via reverse intersystem crossing in TADF molecules.
• Achieved anti-Stokes emission with an energy of 0.18 eV through triplet energy transfer from Ir(ppy)3 to CzBSe.
• Identified that triplet energy transfer rates are significantly influenced by the TADF molecule's triplet radiative decay rate and the energy difference between donor and acceptor.

Conclusions:

• The proposed PUC mechanism offers a promising route for efficient energy harvesting.
• Findings advance the understanding of energy transfer dynamics in organic donor-acceptor systems.
• Potential applications include advanced optical cooling systems and improved energy harvesting technologies.