Automated Research Platform for Development of Triplet–Triplet Annihilation Photon Upconversion Systems

Abstract

Triplet-triplet annihilation photon upconversion (TTA-UC) systems hold great promise for applications in energy, 3D printing, and photopharmacology. However, their optimization remains challenging due to the need for precise tuning of sensitizer and annihilator concentrations under oxygen-free conditions. This study presents an automated, high-throughput platform for the discovery and optimization of TTA-UC systems. Capable of performing 100 concentration scans in just two hours, the platform generates comprehensive concentration maps of critical parameters, including quantum yield, triplet energy transfer efficiency, and threshold intensity. Using this approach, we identify key loss mechanisms in both the established and novel TTA-UC systems. At high porphyrin-based sensitizer concentrations, upconversion quantum yield losses are attributed to sensitizer triplet self-quenching via aggregation and sensitizer triplet-triplet annihilation (sensitizer-TTA). Additionally, reverse triplet energy transfer (RTET) at elevated sensitizer levels increases the upconversion losses and excitation thresholds. Testing novel sensitizer-annihilator pairs confirms these loss mechanisms, highlighting opportunities for molecular design improvements. This automated platform offers a powerful tool for advancing TTA-UC research and other photochemical studies requiring low oxygen levels, intense laser excitation, and minimal material use.