Researchers from the Korea Institute of Energy Research and Chungbuk National University have identified two different types of defects responsible for power loss in silicon heterojunction solar cells. The team, led by Dr. Hee-Eun Song from KIER and Professor Ka-Hyun Kim from CBNU, identified slow and fast component defects using a sophisticated method of Deep Level Transient Spectroscopy that captures the entire transient response of the device.
The study found that the main defect previously thought to be single is actually a superposition of deep and shallow level types. Analysis of each component allowed precise measurement of defect energy levels, their positions within the solar cell, and atomic bonding configuration. Findings indicate that quantitative and qualitative assessments of such defects are necessary to optimize device performance and interaction with passivation technologies.
The team found that atomic bonds can shift at defects depending on the manufacturing method and operating conditions. Hydrogen atoms in the device play an important role in driving these transformations. This research can accelerate the development of highly efficient silicon heterojunction and tandem solar cells, integrating KIER’s proprietary techniques.
“This study will accelerate the development of highly efficient silicon heterojunction solar cells and also enable us to realize world-class tandem solar cells using proprietary KIER technologies,” said Dr. Hee-Eun Song.
“This study provides a fundamental insight into the relationship between defects and passivation,” said Professor Ka-Hyun Kim. “The developed analysis method can be extended not only to solar cells, but also to a wide range of semiconductor and display applications, including sensors, LEDs and CMOS devices.”
Research was conducted using SHJ solar cells manufactured by KIER’s Center for Advanced Solar PV Technology and the analysis was conducted at CBNU. The results form a basis for the future development of tandem solar cells.
Research report:Unraveling mixed-defect transformations and passivation dynamics in silicon heterojunction solar cells
