Larger V_H (Hole Distribution Volume)/V_M (Molecular Volume) Induced Higher Charge Mobility of Group IVA Element-Based Host Materials for Potentially Highly Efficient Blue OLEDs

Abstract

Host materials have a decisive effect on the optoelectronic properties of organic light-emitting diodes (OLEDs), whether for fluorescent, phosphorescent, or thermally activated delayed fluorescence OLEDs. In this work, we first conducted a comprehensive investigation of group IVA element-based small molecular host materials (DCzC, DCzSi, DCzGe, DCzSn, and DCzPb). A multiscale simulation was used to investigate the electronic properties of these materials. The results reflected a novel phenomenon; that is, the hole-transport mobility of DCzC is larger than those of the other group IVA element-based hole-transport materials, which indicated that, compared with the already existing Si-tetraphenyl and Ge-tetraphenyl, the C-tetraphenyl has a higher potential to act as the core moiety to construct high-performance host materials. DCzC has the best hole-transport properties because it has a smaller molecular volume (V M ) while keeping the hole distribution volume (V H ) unchanged, compared with those of the other materials (DCzGe, DCzSi, and DCzSn). This results in a larger V H /V M value for DCzC, which favorably increased the charge transfer integral and improved the hole mobility. This result demonstrated that a larger V H /V M is beneficial in improving the charge mobility of designed host materials. It will be an effective theoretical basis for designing high-performance host materials with excellent charge mobility.

Isomerization of two-dimensional non-fullerene electron acceptor materials for developing high-performance organic solar cells

“…The MC calculations were carried out as described in our previous work. [35][36][37] The adjacent molecular pairs (the shortest interatomic distance is less than 0.5 nm) for each molecule under periodic conditions based on the model of amorphous films were obtained from the MD simulations. The center-ofmass (COM) of each molecular backbone was utilized as the hopping point in the MC simulations.…”

Functionalizing triptycene to create 3D high-performance non-fullerene acceptors

“…The electron mobilities of ITOIC-2F, BFT-3D, and BFTT-3D amorphous thin lms were evaluated by a multiscale simulation based on quantum chemical calculations, molecular dynamics (MD) simulations, and Monte Carlo (MC) calculations, as detailed simulation processes were described in our previous works. 43,52,53 The geometry of ITOIC-2F, BFT-3D, and BFTT-3D are optimized using the quantum chemical calculations as mentioned above. Gromacs 5.1.4 molecular dynamic (MD) simulation package 54 is used to accomplish the MD simulations for all systems.…”

“…The distribution of LUMO signicantly affects electronic transportation. 52 Therefore, the spatial distribution of the frontier molecular orbitals of ITOIC-2F, BFT-3D, and BFTT-3D are inserted in Fig. 2.…”

“…These amorphous lms were used to construct the molecular dimer for electron transport networks as described in our early studies. 43,52,53 To investigate the transfer integral of the whole dimers in these amorphous lms, we showed the normalized distribution of the transfer integral (V) of whole system of BFT-3D and BFTT-3D in Fig. 6(b).…”

“…In addition to absorbing solar energy and separating excitons, the electron mobility of FREAs plays a decisive role in the performance of OSCs because a high electron mobility can facilitate electron transport and collection. Here, we used a multiscale simulation method as described in our early works 43,52,53 to identify the electron mobilities of BFT-3D and BFTT-3D amorphous lms.…”