Advances in Singlet Fission Chromophore Design Enabled by Vibrational Spectroscopies

Abstract

Singlet fission leads to the formation of two separate triplet T1 excitons from an initial singlet S1 exciton through 1(TT) and 1(T...T), multiexcitonic intermediates that retain singlet character. Its ability to achieve external quantum efficiencies higher than 100% made it an attractive candidate for optoelectronic device applications. However, singlet fission has not been applied widely despite having been investigated by a myriad of spectroscopic methods, in part due to our poor understanding of how to optimize molecular structure and packing in chromophores well-suited to large-scale production. Vibrational spectroscopies provide a solution, because they directly probe nuclear motions, allowing us to monitor evolving structural changes in molecules undergoing singlet fission, thus providing us with roadmaps to design molecules suitable for optoelectronic applications. This Perspective reviews the contributions and analyzes the future directions of vibrational spectroscopies to the advancement in our knowledge about the mechanisms and rational designing of chromophores undergoing efficient singlet fission.

Tracking ultrafast reactions in organic materials through vibrational coherence: vibronic coupling mechanisms in singlet fission

“…The frequency-domain techniques thus provide valuable complementary insight into the evolution of the vibrational structure and have played a vital role in investigating the CTmediated mechanism of SF, intermolecular dynamics and the vibrational signatures of 1 TT [89,160]. A detailed description of these and related contributions can be found in the recent review by Frontiera and coworkers [161].…”

Women in the Singlet Fission World: Pearls in a Semi-Open Shell

“…In 2013, the two authors published their second updated review on the topic, recapitulating the newly gained knowledge [7]. Since then, an avalanche of reviews followed [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], and the process of singlet fission has emerged as the frontrunner in the field of organic photovoltaics, attracting the keen interest of more and more researchers from all over the world (Figure 2). Initially, the two triplets are coupled in an overall singlet biexciton ( 1 TT).…”

Femtosecond stimulated Raman spectroscopy – guided library mining leads to efficient singlet fission in rubrene derivatives

“…Vibrational spectroscopies are compelling probes because they can directly probe nuclear motions, thereby monitoring the structural changes in molecules undergoing singlet fission. 28 We have thus previously investigated the structural evolution in crystalline rubrene, the tetraphenyl tetracene derivative shown in Fig. 1a , during SF with femtosecond stimulated Raman spectroscopy (FSRS).…”