In silico prediction of annihilators for triplet–triplet annihilation upconversion via auxiliary-field quantum Monte Carlo

Journal Article · Thu Jan 28 00:00:00 EST 2021 · Chemical Science

DOI:https://doi.org/10.1039/D0SC03381B· OSTI ID:1846311

Weber, John L.  ^[1]; Churchill, Emily M. ^[1]; Jockusch, Steffen  ^[1]; Arthur, Evan J. ^[2]; Pun, Andrew B.  ^[1]; Zhang, Shiwei ^[3]; Friesner, Richard A. ^[1]; Campos, Luis M. ^[1]; Reichman, David R. ^[1]; Shee, James  ^[1]

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1. Department of Chemistry, Columbia University, 3000 Broadway, New York, NY, 10027, USA
2. Schrodinger Inc, 120 West 45th Street, New York, NY, 1003, USA
3. Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA, Department of Physics, College of William and Mary, Williamsburg, VA 23187, USA

The energy of the lowest-lying triplet state (T₁) relative to the ground and first-excited singlet states (S0, S1) plays a critical role in optical multiexcitonic processes of organic chromophores. Focusing on triplet–triplet annihilation (TTA) upconversion, the S0 to T1 energy gap, known as the triplet energy, is difficult to measure experimentally for most molecules of interest. Ab initio predictions can provide a useful alternative, however low-scaling electronic structure methods such as the Kohn–Sham and time-dependent variants of Density Functional Theory (DFT) rely heavily on the fraction of exact exchange chosen for a given functional, and tend to be unreliable when strong electronic correlation is present. Here, we use auxiliary-field quantum Monte Carlo (AFQMC), a scalable electronic structure method capable of accurately describing even strongly correlated molecules, to predict the triplet energies for a series of candidate annihilators for TTA upconversion, including 9,10 substituted anthracenes and substituted benzothiadiazole (BTD) and benzoselenodiazole (BSeD) compounds. We compare our results to predictions from a number of commonly used DFT functionals, as well as DLPNO-CCSD(T₀), a localized approximation to coupled cluster with singles, doubles, and perturbative triples. Together with S1 estimates from absorption/emission spectra, which are well-reproduced by TD-DFT calculations employing the range-corrected hybrid functional CAM-B3LYP, we provide predictions regarding the thermodynamic feasibility of upconversion by requiring (a) the measured T1 of the sensitizer exceeds that of the calculated T1 of the candidate annihilator, and (b) twice the T1 of the annihilator exceeds its S1 energetic value. We demonstrate a successful example of in silico discovery of a novel annihilator, phenyl-substituted BTD, and present experimental validation via low temperature phosphorescence and the presence of upconverted blue light emission when coupled to a platinum octaethylporphyrin (PtOEP) sensitizer. The BTD framework thus represents a new class of annihilators for TTA upconversion. Its chemical functionalization, guided by the computational tools utilized herein, provides a promising route towards high energy (violet to near-UV) emission.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); College of William and Mary, Williamsburg, VA (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: AC05-00OR22725; DE-SC0001303; SC0012704; SC0001303
• OSTI ID: 1846311
• Alternate ID(s): OSTI ID: 1816177
• Journal Information: Chemical Science, Journal Name: Chemical Science Vol. 12 Journal Issue: 3; ISSN 2041-6520
• Publisher: Royal Society of Chemistry (RSC)
• Country of Publication: United Kingdom
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY