Host-only solid-state near-infrared light-emitting electrochemical cells based on interferometric spectral tailoring

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Physics

Background:

• Solid-state near-infrared (NIR) light-emitting electrochemical cells (LECs) offer simple structures and low operating voltages for NIR light sources.
• Conventional host-guest NIR LECs face challenges with increased residual host emission at higher bias voltages, compromising spectral purity for greater NIR output.

Purpose of the Study:

• To enhance NIR light output from LECs without significantly sacrificing spectral purity.
• To explore a novel method for generating NIR electroluminescence (EL) from host-only red-emitting LECs.

Main Methods:

• Proposed a novel approach using host-only red-emitting LECs.
• Adjusted device thickness to modify the microcavity effect and tune constructive interference for NIR emission.
• Investigated the impact of microcavity effects on NIR EL output and spectral purity.

Main Results:

• Achieved NIR EL from host-only red-emitting LECs by optimizing device thickness to shift peak interference to the NIR region.
• Demonstrated that microcavity-enhanced NIR EL is relatively insensitive to bias voltage.
• Obtained a 20× enhancement in NIR output compared to previous host-guest NIR LECs, with minimal loss in spectral purity.

Conclusions:

• Tailoring EL spectra of host-only red-emitting LECs via microcavity effect modification is a promising strategy for high NIR output.
• This method overcomes the residual host emission problem inherent in host-guest NIR LECs.
• The findings pave the way for efficient and spectrally pure NIR light sources based on LEC technology.