Breakthroughs in optoelectronic material technology may bring cheaper and more efficient energy sour

2024-03-07

By using laser spectroscopy in photophysics experiments, researchers at Clemson University have made new breakthroughs, which may bring faster and cheaper energy to drive electronic devices. This new method of using solution treated peroxides aims to completely transform various everyday items such as solar cells, LEDs, smartphones, and photodetectors in computer chips.

Peroxides processed in solution are the next generation of materials that can be used for solar panels on roofs, X-ray detectors for medical diagnosis, and LEDs for daily lighting.

The research group consists of a pair of graduate students and an undergraduate student, guided by Gao Jianbo, the leader of the Quantum Equipment Ultra Fast Photophysics (UPQD) group in the Department of Physics and Astronomy at the School of Science.

This collaborative study was published on March 12th in the highly influential journal Nature Communications. The title of this article is "In situ Observation of Trapped Carriers in Organic Metal Halide Peroxide Films with Ultra Fast Time and Ultra High Energy Resolution".

"Peroxide materials are designed for optical applications such as solar cells and LEDs," said Kobbekaduwa, the first author and graduate student of the research article. "It is important because compared to current silicon-based solar cells, its synthesismuch easier. This can be achieved through solution treatment - and in silicon, you must have different methods, which are more expensive and time-consuming."

The goal of this study is to manufacture materials that are more effective, cheaper, and easier to produce.

The unique method used by the Gao team is to use ultrafast photocurrent spectra, which can have higher time resolution than most methods, to determine the physical properties of trapped charge carriers. In this discipline, measuring data in picoseconds is common, which is one billionth of a second.

"We use this (peroxide) material to manufacture equipment, irradiating it with a laser and exciting electrons inside the material," Kobbekaduwa said. "Then, a photocurrent is generated by using an external electric field. By measuring this photocurrent, we can actually tell people the characteristics of this material. In our case, we defined a 'trap state', which is a defect in the material that affects the current we receive."

Once the physical properties are defined, researchers can identify defects, which ultimately lead to inefficiencies in the material. When defects are reduced or passivated, efficiency can be improved, which is crucial for solar cells and other devices.

Due to the fact that the material is produced through solution processes such as spin coating or inkjet printing, the possibility of introducing defects increases. Low temperature processes are cheaper than ultra-high temperature methods that produce pure materials. But the cost is more defects in the material. Balancing these two technologies can mean obtaining higher quality and more efficient equipment at lower costs.

Test the substrate sample by emitting laser light into the material to determine how the signal propagates within it. Using laser to illuminate the sample and collect current makes this work possible and distinguishes it from other experiments that do not use an electric field.

Adhikari from the UPQD team said, "By analyzing this current, we can see how electrons move and how they emerge from defects.". Thispossible because our technology involves in situ devices under ultrafast time scales and electric fields. Once an electron falls into a defect, those who use other techniques for experiments cannot remove it. But we can remove it because we have an electric field. Electrons have charges under an electric field, and they can move from one place to another. We can analyze their transmission from one point to another within the material. “

The impact of this transmission and material defects on it will affect the performance of these materials and the equipment they use. These are all important discoveries made by students under the guidance of mentors, and the progress created will lead to the next great breakthrough.

Scientists developing new materials can significantly improve the resolution of optical microscopes