Development of Photofunctional Devices Based on Organic–Inorganic Hybrid Structures

Abstract

In this research, organic–inorganic hybrid materials that enable the detection and manipulation of “invisible light” such as weak light, polarized light, and near-infrared (NIR) light are prepared and optoelectronic devices based on these materials are developed. The photoelectric conversion or energy transfer process resulting from light absorption is precisely controlled at the heterointerface of organic–inorganic hybrid structures, which enables the highly efficient amplification, conversion, and detection of invisible light under normal temperatures and pressures. Here, novel optical functions and devices based on organic–inorganic hybrid structures and interfaces are presented. For instance, in a hybrid structure in which organic molecules and inorganic semiconductors are chemically bonded, photocurrent was amplified more than 2000-fold at their heterointerface, resulting in highly sensitive photodetection at a low voltage (<1 V). As a novel device structure for the direct detection of circularly polarized light with high sensitivity, an inorganic crystal thin film with a one-dimensional helical structure was fabricated via interaction with organic chiral molecules. For NIR light, dye-sensitized up-conversion nanoparticles that can convert NIR light as weak as sunlight into visible light with high efficiency were developed and incorporated into a perovskite-based visible-light detector. This device detected light in the NIR region through energy conversion from NIR to visible light. And also, NIR light was promoted as ultra-bright luminescence by one-photon absorption two-photon emission (quantum-cutting) process in heterometal hybridized crystal thin films. The light-emitting diode was fabricated and demonstrated 6 % external conversion efficiency of field emission in the NIR region.

Keywords

• organic-inorganic hybrid
• photofunctional materials
• interface
• energy transfer