To improve the energy conversion efficiency of dye-sensitized solar cells (DSSCs), extension of absorption threshold of the sensitizers to longer wavelength regions is very important issue. In this study, panchromatic photoelectric conversion over 1000 nm using phosphine-coordinated Ru(II) tricarboxy-terpyrine sensitizers (DX1-3) have been accomplished. DX1-3 indicated singlet-to-triplet spin-flip absorption in the near IR region, and DSSC with DX3 showed the photon-to-current conversion efficiency over 80% in the range of 400–880 nm. Furthermore we found 30 mAcm^–1 short-circuit current density under standard sunlight. This result shows the highest value for DSSCs reported to date, but also it is suitable for tandem-type solar cells. Typical organic photovoltaics have been difficult to apply tandem-method in DSSCs because there are no appropriate dyes with high performance in NIR area. In the present study, tandem-type DSSCs employing DX3 and the organometal halide perovskite cell achieved the power conversion efficiency of over 16%.

We report fluorescence-based organic light-emitting diodes (OLEDs) that realize external EL quantum efficiencies approaching to nearly 20% for blue, green, yellow and red emissions, indicating that the singlet exciton production efficiency reached nearly 100%. The high performance is enabled by utilization of thermally activated delayed fluorescence (TADF) molecules as energy donor that permit efficient transfer of all electrically generated singlet and triplet excitons from the energy donor to the conventional fluorescent emitters, i.e., energy acceptor. We revealed that the OLEDs employing this exciton harvesting process also provide significant enhancement of operational stability.

Conjugated polymers are key materials employed in organic optoelectronics such as organic photovoltaics. Upon photoexcitation, singlet excitons are generated first in conjugated polymers while free charge carriers are generated in inorganic semiconductors. Singlet excitons in conjugated polymers are coulombically bound electron-hole pairs and therefore cannot contribute to the photocurrent generation in themselves. To convert charge carriers, singlet excitons should diffuse into heterojunctions such as a donor/acceptor interface. Thus, it is of particular importance to evaluate the exciton diffusion dynamics and length accurately. Interestingly, a singlet exciton can split into two triplet excitons under certain conditions. This multiexciton generation is called singlet fission and has attracted currently increasing attention because it has potential to boost quantum efficiency up to 200%. In this article, we describe singlet exciton diffusion and singlet fission dynamics in conjugated polymer films.

The invention of gold sensitization and its diffusion into the industry are historically reviewed. In 1936 a German company Agfa invented the gold sensitization, led the industry by its distinguished products, but kept the technology secret. A few manufacturers could follow the technology by their own. Many others had to wait the publication of the German technological know-how (PB Repots) after the War. The gold sensitization technology, thus spread, dramatically improved the imagecapturing capability level of films and advanced the whole photographic systems. Some Japanese film manufacturers built their own emulsion technologies on the knowledge base of PB Reports and grew finally to world enterprises.

Dielectric loss method and Maxwell-Wagner theory have been used for ionic conductivity measurements of silver halide grains in the past. For extending these methods to double structured grains, two kinds of silver bromide cubic grains that had different ionic conductivities in shell and core regions were prepared by doping Ir³⁺ ions, and their dielectric loss responses were measured. Pauly-Schwan/Hanai theory which has been applied to the systems with cells or micro-capsules were used for analyzing these results. Good accordance between experiments and calculations was obtained and it was estimated that steep internal electric field could be made in the interface between core and shell regions by considering the space charge layer and the chemical potential.