The efficiency of organic solar cells has reached 20%. In order to achieve 25% efficiency, which is comparable to silicon, it will be essential to suppress all recombinations, especially, geminate recombination, bimolecular recombination, and trap-assisted recombination. In the long term, exciton-free, highly efficient photocurrent generation similar to inorganic semiconductors may be realized.
Thermal energy is generated by all activities that consume energy and dissipate into the environment. However, for the proper function and performance of logic semiconductors, power semiconductors, optical devices, and living organisms, it is important to manage heat appropriately. Accurate understanding of thermal transport requires a deep understanding of the behavior of phonons, the heat carriers. Phonons are more difficult to track and control than photons or electrons, but the exploration of their unique physics and the development of control technologies are progressing steadily. Various applications are introduced, which are opened up by the understanding and control of thermal phonons, based on the fundamentals of thermal phonon transport at the nanoscale.
Owing to its high carrier mobility and weak interaction with phonons, graphene shows remarkable carrier dynamics in the terahertz (THz) range. Here, I show our recent experimental results for active spatial control of graphene plasmons and ultrafast optical to electrical conversion processes in graphene photodetectors. I also explain our on-chip THz spectroscopy method developed for the time-domain measurement of ultrafast electrical current excited at the photodetector.
In organic semiconductors, electron mobilities are lower than hole mobilities. It has not been clear whether this is due to extrinsic factors, such as the electron trap formed by the atmosphere, or the electron mobility is inherently low. We developed angle-resolved low-energy inverse photoelectron spectroscopy and succeeded in measuring the energy band structure (the energy-momentum relation) of the conduction band of organic semiconductor for the first time. Through analysis of the bandwidth, we clarified that the polaron is formed and proposed a new model called partially-dressed polaron. Based on this model, we employed the wave packet diffusion method to calculate the mobilities and proved that the electron mobility is inherently lower than the hole mobility due to the electron-phonon interaction.
Mimicking neural circuits at the hardware level is called neuromorphic engineering and has attracted much attention. In this paper, we show that by mimicking the characteristics of neural circuits using analog circuits and phase transition materials, it is possible to realize IoT technologies that achieves excellent energy-saving performance. Specifically, we will present our recent research to achieve ultra-low power information processing such as circuit control or learning by exploiting neuron circuits that mimic neural circuits, and to achieve excellent two-dimensional sensing with devices that mimic peripheral nerve temperature sensors.
The ALMA telescope, operated in the Republic of Chile, has achieved various results since 2011. In order to continue to lead the field of astronomy, the ALMA telescope will undergo advanced enhancements. This is called ALMA2 in Japan, and one of the most important developments is the wide instantaneous bandwidth of the telescope system. This paper introduces part of the research on wideband technologies for the superconducting receiver frontend.
More than 25 years have passed since industry-academia collaboration took off in Japan, and in recent years it has become increasingly important. In this paper, based on the historical background and the author's many years of experience, the basic process of technology transfer is summarized in a practical manner, and the advantages of technology transfer activities for researchers and points to consider in risk management are also discussed. We hope that this paper will be useful as a guide for researchers at universities and institutions when conducting technology transfer activities.