Reverse Designing the Wavelength-Specific Thermally Activation Delayed Fluorescent Molecules Using a Genetic Algorithm Coupled with Cheap QM Methods

Geneticalgorithm (GA) optimization coupled with the semiempiricalintermediate neglect of differential overlap (INDO)/CIS method ispresented to inversely design the red thermally activation delayedfluorescent (TADF) molecules. According to the predefined donor-acceptor(DA) library to build an AD( n )-type TADFcandidate, we utilized the chemical notation language SMILES codeto generate a TADF molecule and apply the RDKit program to producethe initial 3D molecular structure. A combined fitness function isproposed to evaluate the performance of the functional-lead TADF molecule.The fitness function includes three key parameters, i.e., the emissionwavelength, the energy gap (& UDelta;E (ST)) between the lowest singlet (S-1)- and triplet (T-1)-excited states, and the oscillator strengths for electrontransition from S-0 and S-1. A cheap QM method,i.e., INDO/CIS, on the basis of an xTB-optimized molecular geometryis applied to quickly calculate the fitness function. Finally, theGA approach is utilized to globally search for the wavelength-specificTADF molecules under our predefined DA library, and the optimum 630nm red and 660 nm deep red TADF molecules are inversely designed accordingto the evolution of molecular fitness functions.

Automated summary

This study presents a genetic algorithm (GA) optimization combined with the INDO/CIS method to design TADF molecules. A predefined DA library is used to generate TADF candidates, and the fitness function evaluates their performance. The fitness function considers the emission wavelength, energy gap between S-1 and T-1 excited states, and oscillator strengths for electron transition. The INDO/CIS method is used to quickly calculate the fitness function, and the GA approach is utilized to search for wavelength-specific TADF molecules.