Shedding light on structural, optoelectronic and charge transport properties of PPV stereoisomers for multilayer OLED application: A first principle computational studies

摘要

In the past few years, pi-conjugated polymers, especially PPV derivatives, have been target of intense studies due to their fascinating properties. In this paper, structural, vibrational and optoelectronic properties of a PPV-type pi-conjugated polymer (BPAEt(2)-PPV) displaying three different stereoisomers: Z-Z, E-E and Z-E have been investigated based on density functional theory (DFT) calculations. Theoretical studies were performed in order to justify the chemical structure and also to predict polymer-structure property relationships. Based on TD-DFT and Marcus theories, we have explored the impact of structural configuration on optoelectronic properties and charge mobility. As a result, E-E structure shows a better absorption with a maximum wavelength lambda(max)(abs) = 407.52 nm mainly composed by pi -> pi* electronic transitions and a gap energy equal to 3.39 eV. Similarly, all structures shows a blue emission properties with a best maximum wavelength of lambda(max)(emiss) = 439.18 nm for E-E structure. Furthermore, the theoretical results showed that the electron mobility for E-E structure was high as compared with others configurations with an electron intermolecular charge hopping K-et = 8.54 10(13). While the better hole transport is found for Z-Z structure with a hole intermolecular charge hopping K-ht = 621 10(13). Finally, a numerical simulation, of an organic light emitting diode device using Silvaco TCAD software has been performed and a good enhanced in electrical properties are obtained for E-E configuration compared to Z-Z and Z-E structures with a turn-on voltage of 6.2 V. Based on these interesting results, we have deduced that all structures could be exploited as an active layer in organic light emitting diode. (C) 2019 Elsevier B.V. All rights reserved.