Enhanced Solar Cell Efficiency with Innovative Quantum Dot Technology

A new "pulse-shaped" light method to increase the electrical conductivity of PbS quantum dot solar cells has been developed by a team of researchers. This innovative technique, which eliminates the time-consuming traditional heat treatment process, produces substantial energy at regular intervals and significantly boosts efficiency. It also addresses issues caused by exposure to light, heat, and moisture. Because of their extensive absorption range and low processing costs, PbS quantum dots are now more commercially viable. This progress is likely to promote the widespread use of quantum dot technology in optoelectronic devices.

Under the leadership of Professor Jongmin Choi of the Department of Energy Science and Engineering at Daegu Gyeongbuk Institute of Science and Technology, a research team has successfully developed a “PbS quantum dot” that promptly enhances the electrical conductivity of solar cells. President Wonhwa Hong, Professor Changyong Lim of the Department of Energy Chemical Engineering at Kyungpook National University, and Professor Jongchul Lim from the Department of Energy Engineering at Chungnam National University, led by President Jeongkyoum Kim, collaborated on this initiative.

The researchers have discovered a way to boost electrical conductivity using “pulse-shaped” light, which produces substantial energy at precise intervals. This technology could eliminate the need for heat treatment, a lengthy process traditionally used to achieve similar results. This strategy is anticipated to promote the production and commercialization of PbS quantum dot solar cells in the future.

Studied extensively for next-generation solar cell development, PbS quantum dots are nanoscale semiconductor materials. Their ability to absorb various sunlight wavelengths and their low processing costs due to their solution processing and excellent photoelectric properties make them promising.

The creation of PbS quantum dot solar cells requires several processes. The traditionally essential heat treatment process effectively applies a quantum dot layer to a substrate and enhances its electrical conductivity. However, exposure to light, heat, and moisture can accelerate defect formation on PbS quantum dots, leading to charge reconstruction and performance degradation, thereby complicating commercialization.

A team led by Professor Jongmin Choi sought to mitigate surface defects on PbS quantum dots through a light exposure-based heat treatment lasting only a few milliseconds. Traditional heat treatment techniques for PbS quantum dot layers involve prolonged heating at high temperatures.

A proposed "pulse-type heat treatment technique" by the research team counters the drawbacks of the existing method by using intense light to conduct heat treatment in just a few milliseconds. This process results in minimized surface defects and prolonged travel life for charges (electrons, holes) producing electric current, leading to high efficiency.

According to Professor Jongmin Choi of the Department of Energy Science and Engineering at DGIST, this research has improved the efficiency of solar cells by developing a new heat treatment process that addresses the limitations of existing quantum dot heat treatments. He adds that the development of a quantum dot process with an excellent ripple effect is likely to facilitate the broader application of this technology to various optoelectronic devices in the future.

The National Research Council of Science and Technology of Korea's Creative Allied Project, the Basic Research Lab Project of The National Research Foundation of Korea, and the Regional Innovation Leading Research Center for Carbon-Neutral Intelligent Energy System of Kyungpook National University supported this research. The results were published in the international journal, "Small", with Eonji Lee, a PhD student from the Department of Energy Science and Engineering at DGIST, and Wonjong Lee, an MSc integrated student from the Department of Energy Engineering at Chungnam National University, being co-authors.