In Search of Hosts for Blue OLEDs: Computational Design and Experimental Validation

• Published in: Chemistry : a European journal 2023-03, Vol.29 (18), p.e202203282-n/a
• Main Authors: Thakur, Diksha, Ram Nagar, Mangey, Kumar, Sunil, Shahnawaz, Tomar, Anju, Karmakar, Anirban, Banik, Subrata, Jou, Jwo‐Huei, Ghosh, Subrata
• Format: Article
• Language: English
• Subjects: Aromatic hydrocarbons; Carbazole; Carbazoles; chemical space; Chemistry; Computer applications; DFT-based design; Emitters; Error analysis; experimental validation; host materials; Imidazole; Molecular orbitals; Screening; Searching; virtual screening
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202203282

Considering the difficulties associated with the conventional ‘trial and error’ method for a complete analysis of a giant molecular space, we took the aid of computational pathway (DFT) in screening a large space search of 780 (12×13×5) molecules to search for a host for the blue emitter. The selection process was completed in three Tiers with the conditions of highest theoretical triplet energy (>2.81 eV), aligned HOMO/LUMO levels w.r.t blue dopant (FIrpic), and position of substituents to meet the optimal requirements as host materials. Tier 1 screened twelve different imidazole heterocycle derivatives as base space groups which resulted in the selection of 4,5‐diphenyl‐1H‐imidazole. Tier 2 process converged the search to mCN‐CZ having the highest triplet energy and appropriate HOMO/LUMO level relative to FIrpic and ETL. Further, the carbazole of mCN‐CZ was replaced with different aromatic hydrocarbons to find the other best compound in terms of triplet energy and HOMO/LUMO. Tier 3 resulted in another promising candidate (mCN‐FL) as possible host materials. The band alignment with guest predicted mCN‐FL and mCN‐CZ to have optimal device performances compared to CZ‐CZ and the experimentally observed device performance was in accordance with virtual screening results when TAPC was utilized as the hole transporter. The device results of mCN‐CZ and mCN‐FL were better than the reference host TCTA. The obtained results thus proved that a virtual screening process will be a useful tool for synthetic chemists in designing task‐specific materials. The aid of DFT calculations was implemented for exploring a space search of 780 molecules. The selection process was designed to find material designs with the highest theoretical triplet energy (>2.81 eV) along with suitable HOMO/LUMO levels to accommodate the chosen blue dopant (FIrpic). The outcome of the virtual screening process and corresponding device performances have provided an adventitious outcome that will help discard poor candidates at the virtual screening step.