Inventions Will Improve Performance and Efficiency of LEDs, Solar Cells
By Edwin L. Aguirre
Physics Asst. Prof. Wei Guo and mechanical engineering Assoc. Prof. Fuqiang Liu are among seven early-stage researchers recently awarded funding through the Massachusetts Clean Energy Center (MassCEC) Catalyst Program to develop promising products and technologies in the fields of clean energy and clean water and help bring them to the marketplace.
Guo is creating advanced materials to improve the color spectrum, efficiency and life cycle of white LEDs (light-emitting diodes). LEDs are widely used in a variety of products and applications, from tablets, flat-screen TVs, flashlights and appliances to automotive headlights and general lighting.
Liu, meanwhile, is developing an all-day solar cell that generates and stores electricity simultaneously, allowing it to power lights at night without the need for an external storage battery. Guo and Liu will each receive $65,000 for their respective projects. UMass Lowell is the only academic institution to be awarded funding in this round by the MassCEC; the other grant winners are researchers from private companies based in Boston, Cambridge and Somerville.
“Our efforts to reduce Massachusetts’ greenhouse gas emissions are reliant upon the technology advancements and hard work of our entrepreneurs,” said Energy and Environmental Affairs Secretary Matthew Beaton, who announced the winners on April 18 at the Saab Emerging Technologies and Innovation Center. “This funding provides crucial resources to young companies and promising ideas, supporting clean-tech innovation and job creation in the Commonwealth.”
The fund will help the researchers overcome the challenges of early-stage development, “and help attract additional private investment in the future,” said MassCEC CEO Stephen Pike, who was also on hand for the announcement. “By providing this support we can enable these entrepreneurs and researchers to advance groundbreaking technologies and solutions to the Commonwealth’s energy and water resource challenges,” Pike said.
Lighting the Way
Guo said current “white” LEDs do not really give off pure white light. They produce illumination that has a strong bluish cast, which is not very appealing to the eye.
“The poor color index of conventional white LEDs is largely hindering further development of the LED industry and the LED market’s penetration, especially in residential lighting,” said Guo, who directs the university’s Photonics Research Laboratory.
Guo and his graduate student, Ruizhe Yao, are inventing a new class of phosphor materials for white LEDs that provide high color accuracy. They use nanowires measuring billionths of a meter in thickness that are composed of indium gallium nitride (InGaN) semiconductor material.
“These next-generation nanowire LEDs will improve the users’ experience with any LED-related products, especially where color quality matters the most, such as consumer electronics and residential lighting,” he noted. Guo said InGaN phosphor materials are 20 to 40 percent more energy efficient than conventional phosphor LEDs. They can also extend the life of the LEDs to more than 15 years, compared to only about three to five years for traditional quantum-dot LEDs.
“I hope our technology would attract investment to Massachusetts in the solid-state lighting industry and strengthen the state’s lighting sector,” he added.
Solar Power at Night
Liu’s goal is to demonstrate the feasibility of an all-day solar cell that can provide power for up to five hours at night.
“The solar cell relies on a dual-function electrode that generates and stores electricity at the same time,” he explained. “This eliminates the need for expensive rechargeable batteries used in conventional photovoltaic [PV] systems, which steeply increases the dollar-per-watt price of the electricity produced. Our proposed dye-sensitized solar cell will significantly reduce both the capital and operating costs as well as improve the system’s safety and reliability. Its maintenance-free feature would be useful in the electrification of remote rural areas.”
With an anticipated 50 percent reduction in cost compared to traditional PV systems, Liu estimates that a homeowner will save more than $9,000 in installation for a 5-kilowatt solar cell system. If successful, Liu plans to collaborate with public agencies and private industry to expand the capability of the technology and bring it to market.
Assisting Liu with the lab research are post-doctoral associate Zi Wei and Ph.D. student Husain Almakrami.