Single device harvests and emits light
A newly developed organic semiconductor device can both generate electricity from light and emit bright visible light, as reported by researchers from Science Tokyo.
By carefully designing a material where energy losses are suppressed, the researchers achieved efficient power conversion and electroluminescence simultaneously, demonstrating a multifunctional platform with potential applications in displays, sensors, and energy-harvesting technologies.
In the study 'Highly-Emissive Organic Photovoltaics Approaching Theoretical Limit Voltage and Enabling Multifunctional Energy-Harvesting Displays' published in Advanced Materials on April 20, 2026, the team led by Seiichiro Izawa, tackled a persistent challenge in the field of organic semiconductors.
When light excites these materials, it generates mobile charges—namely electrons and their positively charged counterparts known as ‘holes.’ Ideally, when these charges recombine, they should either produce electricity or emit light. Instead, much of the energy is lost as heat through a process called non-radiative recombination.
To mitigate this issue, the research team focused on controlling how energy flows at the interface between two organic materials. They carefully selected and combined multi-resonance thermally activated delayed fluorescence (MR-TADF) materials, in which electron density alternates across adjacent atoms. This unique arrangement creates an ideal energy-level architecture that prevents captured energy from transferring to non-emissive states.
The researchers used two MR-TADF molecules widely used in OLED technology, called v-DABNA and QAO, in a simple layered structure. Their device achieved 1.36% power-conversion efficiency and 2.0 percent light-emission efficiency simultaneously, marking the first time an organic device has exceeded 1% in both categories. It emitted bright red light with a luminance of 1,000 cd/m2, matching the brightness of commercial smartphone displays. Importantly, the device operated at just 3.2 volts, making it compatible with standard lithium-ion batteries, and achieved an open-circuit voltage remarkably close to the theoretical limit.
Based on these results, the fabricated device approaches the performance of well-established inorganic semiconductors like GaAs. “This demonstration of simultaneous high-efficiency light emission, energy harvesting, and photodetection within a single device establishes a new design framework for organic optoelectronics and represents a significant step toward truly multifunctional, compact, and sustainable device platforms,” remarks Izawa.
Beyond these performance metrics, organic semiconductors offer unique advantages over inorganic alternatives like perovskites. “Organic devices can be fabricated as lightweight, mechanically flexible, and even semitransparent films, making them highly attractive for applications such as window-integrated photovoltaics, wearable and skin-mounted electronics, and conformable display sensor systems, all of which require form factors that are difficult to realize using rigid materials,” explains Izawa.
