MSE Seminar – Prof. Hyeonggeun YU (12 December 2024)

Colloidal quantum dots are promising materials for energy, sensor, and bio-applications. Since the 2023 Nobel Prize in Chemistry, research on the commercialization of quantum dots has gained increased attention, particularly in the field of optoelectronic applications.
In this talk, I will introduce my journey toward developing a new infrared (IR) image-sensing device using PbS quantum dots. The integration of quantum dot films with light-emitting diodes enables a novel imaging concept, such as a pixelless IR imaging sensor. In this device, IR-to-visible image conversion can be achieved in a single pixel, circumventing the need for fine-resolution patterning in traditional image sensor fabrication. For highly efficient IR-to-visible conversion, I will discuss the IR-gating structure and bottom-reflecting structure. Building upon the pixelless imaging concept, the second part of my talk will introduce a new type of device called the ultrasound-to-visible imaging device.
Lastly, if time permits, I will introduce a novel characterization technique called electro-absorption spectroscopy, through which I discovered intriguing excitonic properties in organic bulk heterojunction devices. Excited-state polarizability and dipole moments can be quantitatively characterized in organic blends. We report that electron-donor and electron-acceptor phases can be separately characterized in the blended state due to their complementary absorption spectra.