Chapter 840: Questions left by Professor Xu (two/two)

　　 super large classroom,
Yang Xiaoman is on stage telling about his family history and the case of using finance to like foreign markets, while Xu Mang is sitting in a certain corner, dozing off boredly. It is impossible to imagine that such an airport girl has such a Many students came to attend the class.
　　 Hell...
　　 I feel that Xiaoman is much more famous than himself, what's the situation? Shouldn't these people become more fascinated by themselves?
　　 What is going on?
Xu Mang took out his phone and took a picture of his face, and found that he was still so handsome, even more handsome than before. In the past, he was young and frivolous, and he felt like a chasing teenager. Now he is more mature and stable, I have to say. .. is so handsome.
　　 boring,
Xu Mang took out a pen and a notebook from his bag and began to study the application of perovskite in solar energy. Of course, he cannot do without his mobile phone. Some information can be found online, although there are still a lot of engravings in his brain. But the database is constantly being updated, and I am so lazy...
According to the series structure proposed by Xu Mang, from the point of view of solar energy, the important characteristic of these materials is that the incident light causes the negatively charged electrons to enter a higher energy state, leaving vacancies or holes, which act as positively charged. particle of.
　　If these charged electrons and holes can avoid recombination for a long enough time and reach the electrodes above and below the perovskite film, current can flow.
　　 In theory,
　　 But there are many problems. For the time being, there is no ability to make large-size and high-efficiency battery grids. The problem is that it is more difficult to produce uniform coatings on larger sizes. However, Xu Mang proposed to use transparent electrode films to collect current.
Facts have proved not to work either. These electrode films can allow a lot of light to pass through, but they also have a slight resistance, which will block some currents. In larger sizes, the problems caused by this resistance are more prominent and cannot be expanded like silicon panels. The area thus increases the conversion rate.
Xu Mang simply calculated that the efficiency of a 6.25 square centimeter perovskite battery is 20%, but when 35 grids are combined into a 422 square centimeter module, this One ratio dropped to 12%.
　　 But...
Nevertheless, perovskite batteries are easier to produce and cheaper than silicon batteries. Xu Mang has investigated the process of making silicon, which needs to be heated at 1,800 degrees. When preparing high-purity slabs, the materials need to be heated. Dissolved in three hundred degrees of hydrochloric acid.
　　 On the contrary,
　　 Perovskite batteries only need inkjet printers to deposit a small amount of material on the plastic film.
"Ugh..."
　　 "So annoying!" Xu Mang sighed. If it weren't for his wife, he would have torn off the content earlier. It is not easy to be a man, and it is even more difficult to be a man of Xiaoman.
How to do?
　　 What else can I do, who would let myself marry such a woman?
　　 Putting aside the conversion rate of the perovskite battery, its life is also a big issue. The silicon plates currently in service have 25 years of time, and can the perovskite reach this time? According to the information, there are some difficulties.
also,
Perovskite is also very sensitive to air and moisture, but this can be protected with transparent materials. The most serious is the crystal structure of the perovskite itself, damn... In some cases, it happens when the perovskite heats up. Although structural changes are reversible, they still affect power generation efficiency.
　　 Xu Mang was desperate,
　　 This question is a bit difficult, anyway... let's talk about it when I return to my country.
The next time Xu Mang was very tormented. The ghost knew how it was spent. When everyone in the classroom was finished, Xu Mang was awakened by Yang Xiaoman. He raised his head and looked around and asked in confusion: " What about people? Why are there no more people?"
"It's over!" Yang Xiaoman said angrily: "My old lady, I'm in class, did you not listen to a word? Do you know how long I prepared last night? You big pig's hoof... No respect at all I am mad at me!"
　　 "Ahem..."
　　 "I can't help it." Xu Mang said embarrassingly, "What should I do if I don't understand? I'm so honest, I fell asleep automatically if I didn't understand it. Say... I didn't pay for the speech?"
"No."
"But give me the title of honorary professor." Yang Xiaoman said seriously: "Tomorrow I will have an open class. If you say... stay with me, otherwise I will be nervous. You should not want to see your wife because Are you nervous and suffer from depression?"
　　 Xu Mang: @#￥%……%
I...
Oh my God!
　　 Two days were wasted for nothing, but the vacation can be extended.
　　 left the classroom,
　　 Xu Mang and Yang Xiaoman were planning to visit the scenic spots in the afternoon, but when they passed by the Mathematics Physics and Life Sciences Building, Xu Mang was suddenly stunned. There was a blackboard beside the gate with nothing written on it, and it was empty.
　　 "What's wrong?" Yang Xiaoman asked, "Any problem?"
　　 "It says on this blackboard, the smartest question maker and the most powerful question solver." Xu Mang frowned and said seriously: "Is there no genius in this university?"
"What do you want to do?"
"Don't mess up... People in a foreign land, you have to go to the hometown to do as you like, in case someone else takes a machine gun and beats you to death the next day." Yang Xiaoman stood on tiptoe and gently pinched Xu Mang's Ear, said softly: "Good...otherwise I will beat you up."
Ugh...
　　 spoke the most vicious words in the softest tone.
　　 Damn it!
However, Xu Mang has always been rebellious, otherwise he would not marry Yang Xiaoman. He silently picked up a piece of chalk and wrote a calculation. This process took only half a minute. He turned back and smiled and said, "Let's go... ."
"This..."
　　 "What is all this?" Yang Xiaoman asked with a dazed expression: "What kind of demon are you starting to be?"
　　 "A mathematical formula."
"You need to use the Chen-Hardy-Littlewood theorem." Xu Mang said indifferently: "Although it has not yet reached world-class difficulty, it is enough to make the science students, professors, scholars and experts of Pacific University confused for half a year. time."
　　 "Cut!"
　　 "I don't believe my mother." Yang Xiaoman said disapprovingly: "You are not the smartest in the world, I believe there are smarter than you."
　　 finished speaking,
　　 suddenly sprinkled dog food, holding Xu Mang’s prosperous beauty, with a deep love in his eyes, and said seriously: "But you are the only genius in my heart!"
　　 "Let's go!"
　　 "My knight, this princess wants to eat rainbow ice and ale!"
　　...
in the afternoon,
A Professor Dwyer, who is engaged in mathematics research, took his materials and went to the Mathematical Physics and Life Sciences Building. He just walked into the building and saw that the blackboard on the side was full of content. This abnormality made the mathematics The professor stopped.
　　 It’s been almost a year,
There was content on this blackboard. Although the idea came out two years ago, it only lasted for less than a year, and then everyone’s enthusiasm dropped. The lack of reward mechanism caused many people to lose.了motivation.
　　 Unexpectedly,
　　 It appeared again.
　　 The professor walked a few steps toward the blackboard, and then saw a not-so-complex calculation. At first he didn't take it to heart, but when he was about to solve it, he suddenly realized that the calculation was not as simple as it seemed.
"what..."
"Who wrote this?" Professor Dwyer's scalp is numb at this time. The deeper he goes, the more he feels that this calculation is not simple, and it has completely exceeded the scope of his understanding. According to the truth, it is not like a student writing. Yes, but there are not many professors engaged in professional mathematics. After all, the University of the Pacific is weak in academics and natural sciences.
　　 Damn,
　　 Who actually wrote this bastard's formula?
Professor Dwyer picked up his mobile phone and directly took a picture of the above content, and then directly emailed it to a friend of his. He is a professor of mathematics at Princeton University, who can get together with lunatics. As a professor in the Princeton Department of Mathematics, his strength is extraordinary.
for a long time,
　　 When Professor Dwyer returned to his office from the professor, suddenly his cell phone rang, and it was his friend.
　　 "Dwyko!"
"This...Is this something you came up with?" The professor of the Department of Mathematics at Princeton University, with a hint of surprise in his words, hurriedly asked: "This...this is very difficult. Just now I and other students in the Department of Mathematics The professor researched together and found that... a variety of proofs are needed."
　　 "None of you?" Dwyer asked in surprise, "I know it's difficult, but it can be difficult for you. I'm a little surprised."
　　 "Speaking..."
　　 "Did you come up with this?" the professor asked.
"Do not!"
"I don't know who wrote it. I asked everyone in the Department of Mathematics ~ EbookFREE.me ~ no one admitted." Dwyer suddenly thought of something and hurriedly said: "Right, right... Professor Xu Mang from China was on vacation in Hawaii, and his wife also gave a lecture at our school."
　　"..."
　　 "It must be him!"
"It must have been written by Xu Mang." The professor said solemnly, "The average person can't think of such a difficult calculation, my God... If you encounter it, you must get the answer from him, we people Very anxious now."
"it is good!"
hang up the phone,
Dwyer smiled wryly. He should have thought that this was written by Xu Mang. If someone can achieve such a high achievement in physics, his talent in mathematics would not be too bad. After all, he was engaged in theoretical physics, and it was full of them. A lot of mathematical calculations.
at the same time,
Princeton University,
The mathematics professor is quite speechless. I didn’t think that Xu Mang went to Hawaii, and he came up with a math formula for you. This...this guy is really a headache, but...even though the professor is very concerned about Xu Mang. Very helpless, but the body is very honest.
　　 silently posted this calculation on his Twitter, telling others that this is the calculation given by Xu Mang, I hope someone can solve it, and then attached Xu Mang's current coordinates, located in the Pacific University of Hawaii.
　　 less than an hour,
　　 This tweet exploded directly,
　　 By the way, there is also the University of the Pacific, which is unknown.
　　 The president of the University of the Pacific received countless calls, begging him to keep Xu Mang, at least to keep the answer.
......