Examining the role of acceptor molecule structure in self-assembled bilayers: surface loading, stability, energy transfer, and upconverted emission. Issue 31 (26th July 2018)

• Record Type: Journal Article
• Authors: Zhou, Yan; Ayad, Suliman; Ruchlin, Cory; Posey, Victoria; Hill, Sean P.; Wu, Qiang; Hanson, Kenneth
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 31(2018)
• Page Start: 20513
• Page End: 20524
• Publication Date: 2018-07-26
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp03628d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : This report provides insights into the TTA-UC process with respect to the structure of the acceptor molecule in self-assembled bilayer films. Abstract : Self-assembly of sensitizer and acceptor molecules has recently emerged as a promising strategy to facilitate and harness photon upconversion via triplet–triplet annihilation (TTA-UC). In addition to the energetic requirements, the structure and relative orientation of these molecules can have a strong influence on TTA-UC rates and efficiency. Here we report the synthesis of five different acceptor molecules composed of an anthracene core functionalized with 9, 10- or 2, 6-phenyl, methyl, or directly bound phosphonic acid groups and their incorporation into self-assembled bilayers on a ZrO2 surface. All five films facilitate green-to-blue photon upconversion with Φ uc as high as 0.0023. The efficiency of TTA, and not triplet energy transfer, fluorescence, or losses via FRET, was primarily responsible for dictating the Φ uc emission. Even for molecules having similar photophysical properties, variation in the position of the phosphonic acid resulted in dramatically different Φ TTA, I th values, γ TTA, and D . Interestingly, we observed a strong linear correlation between Φ TTA and the I th value but the cause of this relationship, if any, is unclear.