Chapter 466: A good start

In the group meeting, the perovskite team will report first.
The efficiency of the two-dimensional perovskite stacked device was finally fixed at 10.5%, and Wu Feifei began to write an article, the target journal CM, the current progress is 40%.
For the tin-based two-dimensional perovskite system, Feifei Wu’s summary plan has been written and submitted, and the target journal is ACSEL.
Although Sun Wo caused the device to fall on the street because of the failure of the evaporation equipment last Monday, he made three-wave devices consecutively from Tuesday to Thursday, and increased the device efficiency of the tin-based two-dimensional perovskite from 0.00001% to 1. %, an increase of a full 100,000 times!
However, the current 1% efficiency is still very far from the 12% efficiency results reported by others in "Science".
At the same time, Sun Wo said: "I think the solvent atmosphere has a great influence on the morphology of the tin-based two-dimensional perovskite film..."
Feifei Wu helped to add and explain: "Before the glove box used for mixing perovskite and organic, Sun Wo found that the film was often not coated well. Now he has prepared several batches of perovskite devices, and the quality of the film is clearly visible The efficiency is also improved at the same time..."
Wei Xing pondered for a moment, then turned his head and asked, "Xu Qiu, what do you think?"
Xu Qiu has previously verified through a simulation laboratory that if organic and perovskite are mixed, the performance of the obtained organic photovoltaic device is at least better than that of a pure organic photovoltaic glove box, that is, a glove box made by Gong Yuanjiang. The device efficiency is lower than 0.3%.
But now there are no conditions in the group, so Xu Qiu and others generally maintain the glove box solvent atmosphere before the experiment to reduce the impact of "mixed devices" on device performance.
There are two specific operating methods, namely cleaning and regeneration.
For cleaning, it is simply to continuously exhaust the gas in the glove box to the atmosphere, and at the same time to make up for new nitrogen to come in.
This process still consumes nitrogen. A bottle of high-purity nitrogen costs one hundred yuan, and it can usually be cleaned for about 30 minutes.
Ordinary cleaning operations, coupled with other nitrogen consumption, two glove boxes in the laboratory, generally consume 10 to 20 bottles of high-purity nitrogen a month.
There are generally two situations where cleaning is used.
One is that the glove box causes air to enter the glove box due to broken gloves, improper use of the transfer cabin, over-pressure to open the protective valve, etc., which makes the oxygen content inside the glove box too high, such as greater than 100 ppm.
This requires long-term cleaning, such as five to ten minutes, to reduce the oxygen content in the glove box to tens of ppm, and then let the glove box self-circulate to reduce the oxygen content to a lower level, such as less than 10 ppm.
The other is to clean the device for three to five minutes before preparing the spin-coated effective layer of the device, and "exchange the blood" of the gas inside the glove box in order to obtain a relatively pure nitrogen atmosphere.
This approach has some effects, but it can be regarded as a temporary cure rather than a permanent cure.
Because as the glove box is used for a longer time, many organic solvents will be adsorbed on various surfaces in the glove box, such as the filter, and simple cleaning and ventilation is not enough to remove them.
The manifestation is that the oxygen content of the glove box will remain above 10ppm after the glove box is used for a long time, and cannot rely on its own circulation function, and it will automatically decrease to less than 0.1ppm.
At this time, it is necessary to use the method of regeneration to make the glove box "live again".
The specific method adopted is to heat the place in the glove box where the organic solvent is easy to adsorb, so that the solvent molecules are desorbed at a high temperature.
In addition, a mixture of nitrogen and hydrogen with a volume fraction of 95%+5% is also used to provide a reducing atmosphere.
The regeneration process generally lasts as long as 24 hours, and it cannot be interrupted in the middle, and no experiment can be carried out.
It can be considered that regeneration is a powerful cleaning process.
In this process, the organic solvent molecules accumulated in the box will be excluded from the glove box, most of which will be directly discharged into the atmosphere, and a small part will remain in the laboratory.
Therefore, the taste in the laboratory during this period will be very difficult to describe. Wearing a gas mask, you can smell "astringent" chlorobenzene, DMF and the like.
Therefore, the regeneration time is generally scheduled on Saturday when there is no one.
In addition, the circulation system of the glove box needs to be opened in time after regeneration, so someone needs to come and restart the glove box.
It just so happens that if it is scheduled to regenerate on Saturday, it can be used directly by starting on Sunday.
Of course, regeneration also has a limit, it is impossible to completely restore the state of the glove box.
After all, there are various solvents and reagent bottles in the glove box, and organic solvent vapors are evaporating all the time.
But anyway, the effect of regeneration is much stronger than cleaning.
Generally, the glove box that uses organic solvents can be used continuously for two to three months after one regeneration.
The glove box that almost does not use organic solvents, such as the vapor deposition glove box, can be regenerated once a year.
Xu Qiu deliberated and said:
The atmosphere of the glove box does have an impact on the device results. I also think it is better to prepare organic and perovskite devices separately, but this requires moving the laboratory to Jiangxi. Bend..."
"Moving Jiangwan... it's not impossible." Wei Xingsi considered for a while, and said, "Either our Handan laboratory will move during the winter vacation? It depends mainly on the situation of Xu Qiu and your current laminated device. If you can By posting the article before the winter vacation, we can plan to move during the winter vacation..."
Wei Xingsi paused, and suddenly asked, "By the way, Xu Qiu, how is the latest development of your laminated devices?"
Xu Qiu looked at Duan Yun, Tian Qing, and Chen Wanqing, three of them, and decided to advance the order of their reports. He responded "It's okay" and then inserted the U disk into the computer and started reporting.
He only made one page of PPT this week. The main content is the J-V curve and EQE curve that he tested with his schoolmates last Friday, as well as the optoelectronic performance parameter table of the best laminated device.
Xu Qiu went straight to the point and said: "Last week, Han Jiaying and I achieved the highest efficiency. Hearing this result, everyone was bright.
Mo Wenlin was the one who reacted the most, thinking in her heart:
"It seems that they made a batch of devices last week. That's 16%... Hey, my 15.5%, they were surpassed before they got hot, hum."
Wei Xingsi was still struggling just now whether to move or when to move. Now that he heard the result, he instantly smiled into a chrysanthemum.
He didn't expect that just after the New Year's Day holiday, it would have a good start.
Xu Qiu ignored everyone's reaction and reported calmly:
"The method we adopted this time is to replace the -4F in the previous top cell with a new acceptor material COi8DFIC, and other conditions remain unchanged..."
Hearing this, Chen Wanqing raised her brows, and her own -4F was thus abandoned.
But this is also normal. Its own -4F is considered the earliest near-infrared non-fullerene receptor.
Later, I devoted my main energy to work at Blue River, and it was normal to be surpassed by others without further developing new materials.
Xu Qiu continued to report: "At the same time, we also found that after preparing the device, storing the device in the vacuum environment in the vapor deposition chamber for a certain period of time may improve the performance of the device."
"However, the universality of this phenomenon needs further research."
Although Xu Qiu has made preliminary conclusions in the simulation laboratory, he cannot tell them at this stage.
Tian Qing was originally wandering, hearing the familiar method of "vacuum placement", she instantly shifted her attention.
Her facial expressions are also very rich, and she seems to be talking to Xu Qiu from the air: "Look, I will say that my previous findings are correct, and you don't believe it."
Although Tian Qing has been engaged in the research of device mechanism for a long time, she will do it herself in the early stage and make some standard system devices.
Her discovery was based on the previous P3HT standard sample system, but it was not taken seriously at the time.
Of course, objectively, this is also related to the relatively unstable operation of "vacuum placement".
From Xu Qiu's perspective, he can explore several systems in batches, use a large number of experimental samples, and get a wide range of conclusions, and then use this conclusion to decide his next countermeasure, whether to use this method or not.
For the previous Chen Wanqing and Wu Feifei, they only have one or two systems in their hands, and it is difficult to find the rules. When they find that a method is not so stable and time-consuming, they will naturally not invest in it. Too much energy to study.
Only Tian Qing, who is relatively salty, has been using this method.
After reporting the results of this device, Xu Qiu began to look forward:
"Next, I intend to further optimize, on the one hand, continue to explore the effect of the ‘vacuum placement’ time on the performance of the device."
"On the other hand, referring to the article on the ternary system by Li Dan's research group at the National Center for Nano Science and Technology, the PCBM originally used for the bottom battery was introduced into the top battery to build a binary IDIC-M/ternary COi8DFIC system. , In order to achieve further improvement in device performance..."
Wei Xingsi waited for Xu Qiu to finish all the lectures before he said: I did a very good job! "
Originally, when he first heard about the 16% efficiency result, he planned to let Mo Wenlin or someone go to NIM to send samples for testing.
But when he heard the latter, he was not eager to express his position, because Wei Xingsi heard the 17% possibility of impact from Xu Qiu's confident words.
In the past 15% of the efficiency of submitting to "Science", there is about 20% to 30% of the probability of a successful manuscript, and now 16% of the submission, there may be a 70% to 80% probability of a manuscript. If it can reach 17%, the probability of a manuscript can be increased to 90% or more.
When faced with the unknown and possibly greater opportunities, people are usually accustomed to waiting a little longer.
Just like stocks and funds, when you start to lose money, you always feel that you will be able to repay your capital in a few days. Then, when you return to your capital, you think about whether you can make more money.
At this time, there was a sudden stop, and it fell by five points, thinking that this must be a short-term adjustment, and I want to increase the position.
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On the third day, it rebounded and rose by three points. I recognized my value investment and short-term adjustment ideas very much. I felt that I would continue to rise, so I continued to chase the rise and increase the position.
Then on the fourth day, it fell four points again. At this time, I began to hesitate. I don't think I will fall any more. I should stop the loss in time and clear the position.
As a result, the position was just cleared, and the market just opened on the fifth day, and the daily limit was directly sealed...
It's as if there is a pair of invisible eyes watching you operate.
Wei Xingsi asked casually before, but he didn't expect to "catch a big fish", so much so that he was so excited that he forgot about the moving thing he was discussing.
Therefore, Xu Qiu reminded: "I think this job can be done before the winter vacation, so I can plan to move during the winter vacation."
"Oh, move..." Wei Xingsi reacted and thought for a while and said:
"Then I will talk to the glove box about returning to the factory for renovation. They said that the renovation period is within one month. I greet their boss and try to shorten them to two weeks..."
"In addition, Handan's laboratory has a heavier evaporation equipment, which may be more troublesome to move. I will discuss this with the department and find a professional moving company..."
"Also, the issue of the dormitory, I will apply for this with the faculty at that time, and see if I can arrange you to the Jiangwan dormitory at the same time, but this may be more difficult, I think of a way..."
"Finally, the problem of re-optimizing the experimental parameters. Let's talk about it when we move over. Anyway, we must be prepared to stop work for one or two months, so it is best to deal with all the experiments that need to be processed... …"
After talking about the move, Wei Xingsi switched the topic back: "Xu Qiu, you continue to optimize according to your ideas and see if you can make the performance of the laminated device higher. Now that the "Science" article has been written, it is not good. Efficiency data..."
Wei Xingsi thought for a moment, and then made a final decision: "The time is set before the winter vacation. We will submit this "Science" article, and then the efficiency will be as much as we can achieve."
"Okay." Xu Qiu nodded and agreed. If it really doesn't reach 17% within a month, then he can only give up temporarily.
Otherwise, if someone else achieves an efficiency of 15% or higher after a while, your own advantages will be greatly squeezed.
Xu Qiu reported to the group meeting in advance and skipped three water stroke monsters, Duan Yun, Tian Qing and Chen Wanqing.
In fact, they just don’t have much PPT to talk about.
Duan Yun finally chose Warwick a few days before the expiration of the Warwick offer, so the salary is not high, the monthly salary is 16K, 14 salary, the next step is to sign a tripartite agreement, and then similar to the school sister, first come to Warwick Internship over there.
Tian Qing’s
Research on Charge Transport Related to Multilayer Devices
has officially started work, but since the holiday is approaching, her interest in doing experiments is not very high, and there is no substantial progress.
In order to "pitch the water properly," Tian Qing took the initiative to approach Xu Qiu last week, saying that "I must contribute my own modest effort to the "Science" article in the group."
Translated, it means "I will help you revise the picture, you add me to the list of authors, and then help deal with Teacher Wei's side."
Xu Qiu did not refuse. Journals such as "Nature" and "Science" have very high requirements for pictures. If there are special artists to help revise the pictures, you can add a lot of color to your work and slightly improve the manuscript. rate.
He added Tian Qing's name to the fifth position in the "Science" article, behind Han Jiaying, and the positions of the two undergraduates, senior sister, Gong Yuanjiang, and Wei Xingsi moved one place back.
Like the last "Nature·Energy" article, the current "Science" article is also composed of ten authors.
Chen Wanqing also did not report, paddling in the water.
It stands to reason that students like Duan Yun and Chen Wanqing who are going to graduate can not participate in the group meeting.
However, Wei Xingsi was more stubborn in this regard and made it clear that you can usually not come, but the group meeting must be present.
Next, Han Jiaying began to report that her PTQ1 work has begun to write articles, and the target journal AM also plans to post the articles before the holiday.
She is now in the next semester of her senior year. Because the courses have almost been completed and there is no pressure on the exams, she can devote her main energy to scientific research.
Wu Shengnan continued his previous work on Xu Qiu's Y1-Y4 series of materials, helping Xu Qiu to perform characterization experiments while starting to synthesize. The target products are Y5, Y6, and Y7.
Xu Qiu saw that the system Wu Shengnan chose was partly a system that he had done in the simulation laboratory before but had not made a breakthrough.
However, Xu Qiu is not a good reminder, he can never say that he can be a prophet.
And these systems are pretty good to do, no matter the performance is good or bad, some people still need to do the work.
It's just that Xu Qiu's current goal is to attack the CNS, so he gave up all the leftover work.
For Y series materials, even if it is leftovers, it is not difficult to post a few AM articles.
After all, the efficiency is there. The efficiency of single junction devices exceeds 14%, and no one can beat them at this stage.
Mo Wenlin was busy with exams last week. Because there were two consecutive exams, she spent a week in the experiment.
A few undergraduates did not come to participate in the group meeting, and the academic pressure of their sophomores and juniors is indeed not small.
The newcomer Fan Wentang ran over on Monday.
However, Wei Xingsi did not take the initiative to ask him to participate in the group meeting, and Fan Wentang also did not take the initiative to take the initiative to participate.
After all, it can be regarded as a period of mutual investigation between students and tutors, and it is not suitable for excessive participation in various matters of the research group.
Especially now that the group is in a critical period of impacting "Science", we still have to avoid suspicion.
In the next few days, Xu Qiu continued to revise the "Science" article while preparing laminated devices.
To be precise, it is to look at other people preparing stacked devices.
The experimenter changed from the original school girl to Mo Wenlin. Because the latter had already finished the exam, she was relieved.
The school girl changed her taste and made a batch of devices, and then returned to writing articles about her PTQ series donor work.
The main reason was that after Xu Qiu came up with the experimental conclusion of "vacuum placement", he basically ruled out the influence of the experimenter, and did not let the schoolgirls continue to make the devices again.
This week, Xu Qiu has the last exam, which requires an open-book exam and a PPT presentation at the same time. The type is similar to the previous "Inorganic Functional Materials" and "Composite Materials", and he thinks it can be easily won.
Xu Qiu estimates that the three major courses in this semester are likely to be A, plus one exempt English course and one "Laboratory Safety Education" with a grade of P (passed).
Calculating, the full grade point of more than 10 credits is still very powerful.
Of course, this is mainly related to the relatively "pure" course arrangement during the postgraduate period, most of which are professional courses.
In the undergraduate course, many political courses and general elective courses were mixed.
In these courses, you need to compete with liberal arts students.
And Xu Qiushi is a PK but their liberal arts students, so he took a lot of B and B+, and his grade point was pulled to 3.5.
The reason why the PK is not good is that liberal arts students, such as international economics and trade majors, have very few places for undergraduate studies, and they are very small.
A grade point above 3.6 is the bottom of the insurance research team.
Therefore, they must strive to get A in every subject.
The materials department requires a grade point of 2.8 for postgraduate guarantee. When actually admitted, the grade point requirement is about 3, that is, students with an average grade of B can be guaranteed postgraduate.
Because there are many B+ unlimited courses, even if there is not a course that can get A, as long as it is not too watery, you can guarantee it if you want to apply for it.
Of course, due to the existence of involute, the threshold of the materials department will be higher and higher.
It is said that in the previous session, that is, Tian Qing, 2.8 can get it, and now Xu Qiu is already 3.0 in this session, and it may take 3.2, 3.4... to get the research and insurance.
In addition to his own course exams, Xu Qiu also has the status of teaching assistant this semester, and needs to be invigilated during the exam week.
Generally, teaching assistants will participate in the invigilation of their courses, but because Wei Xingsi's course does not have an exam, Xu Qiu was assigned to other courses.
It's another undergraduate course called "Smart Materials", a closed-book exam, located in the West Annex of the Twin Towers.
Xu Qiu came to the classroom ten minutes before the scheduled test time. The candidates here were almost there, and the teacher was already standing on the podium with a stack of test papers in hand.
The teacher of this course is named Wang Jizeng, an associate professor of green pepper. He is not very present in the department, and he is not very old. He is in his early thirties, but his hair is already a little sparse.
Wang Jizeng and Xu Qiu nodded friendly, and there was not much to say.
The internal invigilation of this kind of faculty is relatively casual, and it is not too strict.
Cheating naturally exists.
Every year, Modu University is caught for cheating, and then punished. Basically, it is to stay on campus to observe and start, and even get expelled.
There was a girl who helped her boyfriend take the high math test, but was caught. The girl and her boyfriend were both fired. Emmm...
It is said that the sister's parents came over and cried very much, but it was of no use.
Because they were arrested as a model at the time, the punishment was very heavy.
This is the same as the country's severe crackdown. If something is committed during the normal period, if there may be a minor problem, it will be released after a few days of detention.
Just caught up, I can only say bad luck.
Because of this kind of thing, only the tip of the iceberg is exposed, and the majority are not exposed.
At least Xu Qiu had witnessed cheating by students from the perspective of the examinee during the previous exam no less than ten times.
On one occasion, someone was arrested at the scene, but the teacher just confiscated the other party's tools for committing crimes and did not pursue them.
Most teachers are more "kind".
The bell rings ~EbookFREE.me~ The exam begins.
The Twin Towers may be used for both office and teaching purposes, so they don’t have the same bells as the second, third, and fourth schools, but instead use a melodious bell.
After Xu Qiu helped Wang Jizeng hand out the test papers, he found a seat in the back row and did not plan to take the initiative to go out for inspections.
Wang Jizeng sat on the podium.
Invigilation is quite boring, because you can only sit for a long time, and in principle you can't play with your mobile phone.
Before Xu Qiu saw a teaching assistant because he was too boring, so he asked the teacher for a set of papers and did it himself...
However, Xu Qiu has a way to kill time. He went directly to the simulation laboratory to check the results of the past few days.
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