▲ Professor Seok Sang Il. Provided by Professor Seok Sang Il
What would it feel like if there were no nuisance to charge one’s phone battery because the small solar cell attached to the phone would automatically charge using solar energy? This ideal imagination has come a step closer to reality as a plethora of researches on solar cells have been showing fruitful results. These are expected to generate a fresh windfall of positive possibilities to the solar cell industry.
A Solar cell, simply put, is the turning of the sun’s light energy into electrical energy. Unlike energy using nuclear power or coal, solar energy is sustainable in that it utilizes the sun, which does not disappear. In that sense, solar energy exists as ecofriendly energy, and a suitable solution for environmental pollution. In fact, the Moon administration has set a “ R e n e w a b l e e n e r g y 3 0 2 0 ” implementation plan which aims at raising the percentage of the development of replaceable energy up to 20 percent until 2030, thus creating a lot of solar energy power stations.
Is It a Real Potentiality?
Along with the optimistic point of view toward solar energy, there seem to be negative voices concerning the effectiveness of it. First, sunlight generation needs a great amount of land, which becomes a critical hardship in Korea due to the high density of population and numerous mountain areas. Also, its basic generation cost is quite high. Despite its potentiality, those limits make the speed and efficiency of solar energy generation low and frustrating.
Above all, the foremost issue is the low conversion efficiency of solar cells. Conversion efficiency refers to the criterion of how much electrical energy the incident solar rays produce through the solar cells. In other words, solar batteries that produce more electric through solar energy, under the same condition, have a higher conversion efficiency. The average conversion efficiency of solar energy generation is known as eight to 15 percent, which is very low compared to 45 to 50 percent of thermal power generation and 30 to 40 of nuclear power generation.
The Center of Solar Energy, Perovskite
Despite those limits, since solar energy is pure and infinite, there has been a plethora of research by various research teams. The center of recent solar battery is without doubt, a material called, perovskite. Perovskite refers to a metallic oxide with a special structure that even shows superconductivity and has all the characteristics of a nonconductor, a semiconductor, and a conductor. The very beginning of the use of this material was in 2009, when a research team at Toin University of Yokohama used the material in a threedimensional structure. However, at that time, the use of liquid electrolyte reduced the long-term safety of the battery, and the efficiency was just about three to four percent. This led to the inactive research in this field.
The main limits of the perovskite solar cells were its instability in structure. A research team led by Professor Seok Sang Il (School of Energy and Chemical Engineering, Ulsan National Institute of S cience and Technolog y) ha s succeeded in stabilizing the structure by adding both methyl ammonium cations and bromide anions. However, this was not the end of the problem. Professor Seok mentions, “Our team could solve the instability with this method, but the addtion of methyl ammonium and the bromide ion has resulted in the widening of a bandgap and damage in t h e s o l a r e n e r g y a b s o r p t i o n wavelength.” In November, Professor Seok and his team was able to solve this problem by adding a new additive, called methylenediammonium chloride. With the additives, both the stability of the structure and an adequate level of efficiency could be kept.
Nevertheless, there are still remaining hardships in the development of solar energy using perovskite. Since perovskite is very sensitive to humidity, it undergoes a decomposition process in a humid environment which reduces its conversion efficiency dramatically. Considering that the high effectiveness is the very strength of it, the key point is t h e r e s e a r c h o n s y s t e m a t i c management of environmental conditions. Fortunately, recent research suggests that the vulnerability to moisture could be solved by a process called encapsulation.
One Step Forward
After professional institutions’ efforts on the production of efficient and also safe cells, the remaining task is in what way those cells could be used. In fact, most people think of dim black plates that are not beautiful when it comes to solar farms. However, a glance at the “Easy House,” a zero-energy house in Seoul, Nogye-dong, can change people’s stereotypes, since the cells make a great harmony with surrounding structures. Now, it is time for solar batteries to naturally and beautifully permeate structures. With diverse colors and sizes, it is no doubt that solar cells could be transformed into one of the important elements in architectural design.
In addition to permeating buildings, cells could be transformed into a practical facility that would greatly give useful help in real lives. For instance, there are benches that use the light of the sun, in which one can even charge their cell phone battery with the stored energy. There are also streetlamps that light up the dark using the energy accumulated in the daytime. According to Professor Seok, “Diverse research is being carried out to make the best use of solar cells’ lightness, flexibility and high conversion efficiency, which utilizes the cells as the basic energy source for mobile devices, drones and unmanned equipment.”
Furthermore, at the 2018 Seoul Sunlight Expo, there were various booths where people could experience interesting activities using solar energy techniques, which include cooking simple foods and making small fans. These kinds of activities will also, in the long term, encourage citizens to become more solar energy-friendly.
Solar energy, despite doubts on its practicality, seems to be holding power as a great promising renewable energy, with the assistance of passionate research. The steady development of solar cells in terms of conversion efficiency, stability and safety is crucial, which would require continuous support from the government. Furthermore, with applications of those developed cells to daily lives after a conversion into a more friendly form, solar energy generation, without doubt, would be able to hold its place as a |Professor Seok Sang Il potential energy alternative.