Enhanced Stability of Perovskite Solar Cells Through the Development of New Additives
December 7, 2016 | NIMSEstimated reading time: 2 minutes
A NIMS research group led by Liyuan Han, Managing Researcher, Center for Green Research on Energy and Environmental Materials, developed new additives for the hole-transporting layer of perovskite solar cells, which greatly improved cell stability (Advanced Materials, "Enhanced Stability of Perovskite Solar Cells through Corrosion-Free Pyridine Derivatives in Hole-Transporting Materials").
a) Schematic of a perovskite solar cell in a normal structure. b) Molecular structures of an existing pyridine derivative (left) and a new pyridine derivative with an alkyl group (blue) attached (right).
When placed in the dark, the cells did not show signs of deterioration even after 1,000 hours of testing, and under continuous light soaking, they lasted six times longer—in terms of the time it takes for their power conversion efficiencies to fall to 85% of their initial states—compared to cells treated with conventional additives.
Thus, the new additives greatly enhanced cell stability. The researchers hope that these results will accelerate efforts toward practical application of perovskite solar cells.
Perovskite solar cells, which can be manufactured by solution processes, have attracted much attention since their power conversion efficiency have exceeded 20%. Though their conversion efficiencies are steadily increasing, their stability remains as a major issue.
For example, perovskite solar cells in a normal structure, consisting of titanium oxide, perovskite and a hole-transporting layer, demonstrate the highest conversion efficiency, but they have very poor stability, and their conversion efficiencies decline about 30% after 200 hours of testing even under dark.
Therefore, key issues for practical applications of these solar cells are to understand the causes of poor stability and development of new materials to improve the stability.
Recently, the research group directed their focus on a pyridine-based additive, TBP, which is used as an additive in a hole-transporting layer in the mesoporous-type cell structure. After conducting experiments and analyzing the results, the group found that chemical reactions occurring between TBP and perovskite materials were one of the major cause of stability deterioration.
Moreover, analyses using infrared spectroscopy and X-ray diffraction revealed that the chemical reaction mainly occurs between the nitrogen atom in the pyridine ring and perovskite crystals. The group successfully suppressed this undesirable reaction by adding an alkyl group to the position close to the nitrogen atom, leading to a steric hindrance effect (prevention of two reacting atoms from nearing each other in space).
Consequently, perovskite solar cells that contained the new pyridine derivatives maintained their performance over 1,000 hours in the dark. In addition, under continuous light exposure, application of conventional additives made cells last for slightly less than 25 hours, which is the time it took for the cells’ conversion efficiencies to decrease to 85% of their initial states.
In contrast, application of the new additives made the cells last for 150 hours. That is, the cells’ stability was increased by six times.
The research group first identified mechanisms of perovskite solar cell deterioration, then developed a new material based on the findings. This study demonstrated that the group’s approach is very effective in terms of improving the stability of solar cells. We will further investigate factors influencing solar cell stability, and continue to develop new materials with the aim of achieving practical use of perovskite solar cells as early as possible.
A part of these results was produced by implementing the project “Development of technology to reduce the cost of high-performance and high-reliability solar power generation,” sponsored by the New Energy and Industrial Technology Development Organization (NEDO).
Suggested Items
SMC Korea 2024 to Highlight Semiconductor Materials Trends and Innovations on Industry’s Path to $1 Trillion
04/24/2024 | SEMIWith Korea a major consumer of semiconductor materials and advanced materials a key driver of innovation on the industry’s path to $1 trillion, industry leaders and experts will gather at SMC (Strategic Materials Conference) Korea 2024 on May 29 at the Suwon Convention Center in Gyeonggi-do, South Korea to provide insights into the latest materials developments and trends. Registration is open.
Groundbreaking Ceremony Marks the Beginning of a New Era for Newccess Industrial; The Construction of the MINGXIN Building
04/12/2024 | Newccess IndustrialOn a clear and sunny day in March, the groundbreaking ceremony for the MINGXIN Building took place in Shenzhen, China. This moment marked the official commencement of construction for a project that will reshape the semiconductor materials industry.
The Need for a Holistic Global Sustainability Standard
04/10/2024 | Michael Ford, Aegis SoftwareNo one can deny that the resources of our fragile planet are finite. The environment seems like a third party, subject to constant degradation. We’re acutely aware of the effects of pollution on our climate, and despite our “throw-away” culture, recycling and recovery of materials has remained relatively expensive, even as we use more energy just to survive.
iNEMI Publishes Four Roadmap Topics
04/04/2024 | iNEMIThe International Electronics Manufacturing Initiative (iNEMI) announces the availability of the first roadmap topics in the new iNEMI Roadmap format. Printed circuit boards, sustainable electronics, smart manufacturing, and mmWave materials and test are now available online.
Insulectro’s 'Storekeepers' Extend Their Welcome to Technology Village at IPC APEX EXPO
04/03/2024 | InsulectroInsulectro, the largest distributor of materials for use in the manufacture of PCBs and printed electronics, welcomes attendees to its TECHNOLOGY VILLAGE during this year’s IPC APEX EXPO at the Anaheim Convention Center, April 9-11, 2024.