All-Solution Processed Single-Layer WOLEDs Using [Pt(salicylidenes)] as Guests in a PFO Matrix

José Carlos Germino; Luís Gustavo Teixeira Alves Duarte; Rodrigo Araújo Mendes; Marcelo Meira Faleiros; Andreia de Morais; Jilian Nei de Freitas; Luiz Pereira; Teresa Dib Zambon Atvars

doi:10.3390/nano12142497

All-Solution Processed Single-Layer WOLEDs Using [Pt(salicylidenes)] as Guests in a PFO Matrix

Nanomaterials (Basel). 2022 Jul 20;12(14):2497. doi: 10.3390/nano12142497.

Authors

José Carlos Germino^{1

2}, Luís Gustavo Teixeira Alves Duarte¹, Rodrigo Araújo Mendes³, Marcelo Meira Faleiros¹, Andreia de Morais⁴, Jilian Nei de Freitas⁴, Luiz Pereira², Teresa Dib Zambon Atvars¹

Affiliations

¹ Chemistry Institute, University of Campinas-UNICAMP, Campinas 13083-862, Brazil.
² Department of Physics and i3N-Institute for Nanostructures, Nanomodelling and Nanofabrication, University of Aveiro, 3810-193 Aveiro, Portugal.
³ São Carlos Institute of Chemistry, University of São Paulo-USP, São Carlos 13566-590, Brazil.
⁴ Center for Information Technology Renato Archer-CTI, Campinas 13069-901, Brazil.

Abstract

Herein, we report the synthesis and characterization of two Pt(II) coordination compounds, the new platinum(II)[N,N'-bis(salicylidene)-3,4-diaminobenzophenone)] ([Pt(sal-3,4-ben)]) and the already well-known platinum(II)[N,N'-bis(salicylidene)-o-phenylenediamine] ([Pt(salophen)]), along with their application as guests in a poly [9,9-dioctylfluorenyl-2,7-diyl] (PFO) conjugated polymer in all-solution processed single-layer white organic light-emitting diodes. Completely different performances were achieved: 2.2% and 15.3% of external quantum efficiencies; 2.8 cd A^-1 and 12.1 cd A^-1 of current efficiencies; and 3103 cd m^-2 and 6224 cd m^-2 of luminance for the [Pt(salophen)] and [Pt(sal-3,4-ben)] complexes, respectively. The Commission Internationale de l'Eclairage (CIE 1931) chromaticity color coordinates are (0.33, 0.33) for both 0.1% mol/mol Pt(II):PFO composites at between approximately 3.2 and 8 V. The optoelectronic properties of doped and neat PFO films have been investigated, using steady-state and time-resolved photoluminescence. Theoretical calculations at the level of relativistic density functional theory explained these results, based on the presence of the Pt(II) central ion's phosphorescence emission, considering spin-orbit coupling relationships. The overall results are explained, taking into account the active layer morphological properties, along with the device's electric balance and the emitter's efficiencies, according to deep-trap space-charge models. Considering the very simple structure of the device and the ease of synthesis of such compounds, the developed framework can offer a good trade-off for solution-deposited white organic light-emitting diodes (WOLEDs), with further applications in the field of lighting and signage.

Keywords: photoluminescence; platinum(II) complexes; solution-deposited devices; white-OLED.

Grants and funding

J.C.G. and L.P. acknowledge the Institute for Nanostructures, Nanomodeling and Nanofabrication (i3N) of the Portuguese Foundation for Science and Technology (FCT) (UID/CTM/50025). J.C.G., L.G.A.T.D., M.M.F. and T.D.Z.A. acknowledge FAPESP (2013/16245-2), CNPq (470529/2012-1) and 458413/2014-3), the National Institute of Organic Electronics (INEO) (MCT/CNPq/FAPESP), and UNICAMP/FAEPEX for financial support and fellowships. A.d.M. and J.N.d.F. acknowledge the Center for Information “Renato Archer” (CTI). R.A.M. thanks R.L.A. Haiduke for valuable discussions and orientation. R.A.M. also thanks the Center for Mathematical Sciences Applied to Industry (CeMEAI)-FAPESP 2013/07375-0 for the use of their computational resources. The authors acknowledge the assistance of Maria João Sá Pereira in performing the atomic force microscopy experiments.