Photodetectors are devices that convert light into electrical signals. They are found everywhere, from smartphone cameras to telescopes in space and even form the backbone of communications networks.
In a new study, researchers from the Indian Institute of Technology Delhi (IIT Delhi) have unveiled a novel photodetector that could significantly enhance high-speed communications and imaging. Their newly devised Metal-Semiconductor-Insulator-Metal (MSIM) photodetector is self-powered and achieves ultra-fast performance and sensitivity.
Postdoctoral researcher Rakesh Suthar, along with Suryakant Singh, led the work under the guidance of Prof. Supravat Kara at IIT Delhi. Part of the research was also conducted at Nagoya University under the JSPS Invitational Fellow program in Prof. Kunio Awaga's laboratory.
“Our aim was to create a high-speed, self-powered photodetector that promotes next-generation optical communication while conserving energy,” said Prof. Supravat Karak about the goal of the study
Photodetectors are key components in optical communication. As particles of light or photons strike the material, they knock out electrons, which causes a small voltage potential. In traditional photodetectors, this voltage is minuscule and needs to be amplified with an external power supply to detect the photon. The newly devised Metal-Semiconductor-Insulator-Metal (MSIM) photodetector overcomes this limitation and can operate without external power while maintaining an ultra-fast response and high sensitivity across the visible to near-infrared (NIR) spectrum.
Conventional silicon (Si) and gallium arsenide (GaAs) photodetectors, demand elevated bias voltages to amplify the current. In the new MSIM design, however, when light hits the device, it triggers the generation of transient photocurrent signals that alternate polarity as the light is turned ON/OFF. In this case, the current is high enough to be detected without any external voltage bias. This characteristic helps in producing signals that are more clearly distinguishable, ultimately enhancing the reliability and speed of data communication.
To fabricate the MSIM photodetector, the researchers employed organic semiconductors—specifically a polymer called PM6, which acts as the donor, paired with an acceptor molecule Y6. This organic semiconductor is then combined with a thin parylene dielectric layer arranged in a metal-semiconductor-insulator-metal configuration.
“This study illustrates how organic semiconductors can be harnessed to develop efficient and ultra-fast optoelectronic devices, supporting advances in high-speed communication and advanced sensing,” remarks Dr. Rakesh Suthar.
The team’s MSIM photodetector has already showcased its potential by demonstrating real-time infrared communication using ASCII codes. In this demonstration, the device rapidly converted optical pulses into accurate electronic signals for data transfer. With the ability to operate at high frequencies (up to 5.6 MHz) and offer fast response times, this self-powered photodetector is poised for broader deployment in any system that demands high-speed communication—whether in telecommunications infrastructure, industrial sensing, or even emerging quantum technologies where photon-level sensitivity is critical.
This cutting-edge technology also shows immense potential for quantum applications, particularly in single-photon detection and high-frequency communication. Future evaluations under the “Quantum Mission” project, headed by IIT Delhi and funded by DST, will further explore its capabilities.
While the technology demonstrates impressive speed and sensitivity, there are a few areas for future research and development. Organic semiconductor materials can face issues related to long-term stability, particularly under varying environmental conditions. Researchers will need to explore encapsulation strategies and material modifications to ensure durability under real-world conditions and extended operation. Furthermore, to integrate this concept into large-scale manufacturing, it will be important to refine fabrication methods to maintain consistency and cost-effectiveness.
The novel MSIM photodetector marks a significant leap toward faster, more energy-efficient optical communication systems. By harnessing the unique properties of organic materials, the researchers have laid the groundwork for new generations of flexible, self-powered devices, opening doors to advancements in high-speed data transfer, sensing technologies, and beyond.
This article is based on a Press Release from the Indian Institute of Technology Delhi (IIT Delhi).
This research article was written with the help of generative AI and edited by an editor at Research Matters.