Fully integrated electrochromic-OLED devices for highly transparent smart glasses

Abstract

The integration of energy-saving electrochromic systems with novel functions and features in a single smart multifunctional device promises to achieve remarkable technological advancements for a wide range of consumer products showing more versatility, responsivity to different external inputs, and ability to operate in interactive modes. Here, we report a novel architecture in which a solid-state electrochromic cell and a solid-state organic light emitting diode are fully integrated in a single, highly transparent, solid-state electrochromic OLED device. This multifunctional device is capable of tuning its optical properties such as transmittance (chromic transition) and of producing light by electroluminescence, simultaneously or independently. The rational design of the solid-state electrochromic cell and the highly transparent OLED enables the construction of the integrated device in a monolithic unit. In such a structure the photonic architecture of the OLED device not only guarantees high transmittance, but, operating synergically with the electrochromic component, it outperforms the optical properties and electrochromic responses by the interference phenomenon, achieveing an optical contrast of 57% (ΔT_{bleaching/colouring} @ 650 nm), and a coloration efficiency of 169 cm² C⁻¹, with very low energy consumption (80 mW cm⁻²). The OLED component exhibits luminance above the minimum values required for display and lighting applications, which are 300 cd m⁻² and above 800 cd m⁻², respectively. This result represents a further step towards the development of next-generation multifunctional EC devices such as full solid-state photoelectrochromic devices, and, importantly, this can open the way for new electrochromic “smart” window systems such as retail display windows or display EC glasses for augmented reality.