Anomalous redshifted emission in Pt(ii) vs. Ir(iii) complexes with identical ligands and the application of these complexes in high-efficiency OLEDs

Abstract

Conventionally, Ir(III) complexes typically show longer emission wavelengths compared to their Pt(II) complexes with identical ligands. In this work, a series of Pt(II) and Ir(III) complexes based on identical benzothiophene ligands were designed. Experimental results demonstrate that the Pt(II) complexes exhibit red-shifted emission compared to the Ir(III) complexes. This is caused by the lower T₁ energy level of the Pt(II) complexes. The device efficiency prepared by vapor deposition can reach up to 20.3% with very small efficiency roll-off, demonstrating superior performance among Ir(III) complexes bearing thiophene and related structures. Furthermore, the broader spectrum of Pt(II) complexes makes them suitable for applications in white light devices.