Chapter 454: Xu Qiu is out of the circle again, and the driving force behind the scenes turned out to be...

After getting 15% efficiency data, Xu Qiu began to plan the optimization direction of the next laminated device.
In the current optimal system, the effective layer of the bottom cell is the ternary J4:PCBM:IDIC-4F system, and the effective layer of the top cell is the binary PCE10:-4F system.
Considering that the Y-series acceptor has fallen on the stacked device, Xu Qiu is also thinking about whether the IDIC-4F is also a bit too perfect, which squeezes the space of the top cell and reduces the overall stacking device. Upper limit.
After all, when the initial screening of the effective layer materials for laminated devices was carried out, the main reason why the IDIC-4F system was chosen was because its efficiency was high enough.
In the later exploration process, Xu Qiu made little changes to the effective layer material, and has been using the IDIC-4F system.
In addition to using the ternary strategy to introduce PCBM, it is basically doing optimizations related to the transmission layer, reducing light loss as much as possible, improving the effect of charge transfer, and so on.
Therefore, the optimization of the processing technology at this stage can be said to be relatively complete.
To make further breakthroughs, most of them still need to be based on a reasonable choice of effective layer materials.
As a result, Xu Qiu made the decision to shift the focus of optimization of laminated devices to the selection of materials again.
On the one hand, when selecting materials for the top and bottom cells, the considerations can be broader, instead of taking the initial efficiency of the binary system as the main reference standard.
Instead, it mainly considers the adaptation of light absorption, so that the top cell and the bottom cell can perform their duties. The top cell mainly absorbs short-wavelength light, and the bottom cell mainly absorbs long-wavelength light.
On the other hand, Xu Qiu intends to broaden the choice of materials to cover the entire field of organic photovoltaics, rather than limited to materials developed by his team.
With the development of ITIC, other research groups have also developed many excellent donor and acceptor materials in the past six months. If appropriate, they can also be used directly.
Especially when it comes to the choice of near-infrared non-fullerene receptors for the bottom battery, Xu Qiu is not very satisfied with the series of senior sisters, and the materials such as FN-4F developed by senior sisters.
These materials do not have much problem in terms of efficiency, and they are all 12% systems.
However, their device performance is somewhat affected by the effective layer thickness. Once the thickness deviates too far from the optimal film thickness, the device efficiency will fluctuate greatly. For example, if the thickness is 300 nanometers, the device efficiency may be directly cut in half. Up.
In a laminated device, because the short-circuit current density of the top cell and the bottom cell needs to be adjusted, the effective layer needs to be less sensitive to changes in film thickness.
For example, IDIC series materials are a good choice. The film thickness is from 100 nanometers to 300 nanometers, and the performance of the device itself does not change much.
During this time, Xu Qiu also selected several materials from other research groups and synthesized them in a simulation laboratory based on their articles.
The reason for not buying directly is because at this stage, in addition to Xu Qiu’s ITIC, IDIC, and series, as well as Xu Zhenghong’s IDTBR series of non-fullerene materials, which are more dominant in the market, the materials developed by other research groups are basically There are no channels for commercialization.
Even if you want to buy it, you have to find a photoelectric company to make it, and buy it in large quantities of 5 grams and 10 grams.
Because materials are time-sensitive, new and better materials may be developed in a few days.
If an old material has no characteristics, it will most likely not be sold after the new material comes out.
Although the ITIC, IDTBR series are early materials, because they appeared early enough, they have now become standard materials.
Many research groups that are unable to independently develop new materials will buy standard materials to do ternary, stability and other leftovers.
Therefore, the standard materials are not worried about selling, which is why Xu Qiu asked Blue River Optoelectronics to make ITIC first when it first stocked up.
In addition, the IDIC series are easy to understand because they are the best-performing materials at this stage.
Among the materials developed by other research groups, Xu Qiu noticed the latest reports that a non-fullerene acceptor material called COi8DFIC is quite interesting, and he has already included it as a focus of attention.
The molecular structure of COi8DFIC is somewhat similar to the DBC-IC previously reported by Zhenghong Xu's group in the NC article.
The central D unit also adopts a non-fully conjugated fused ring structure. The three TT units are first connected via a carbon-carbon single bond. At the two junctions, they are extended with an oxygen atom and a carbon atom respectively, and the surrounding two Each TT unit forms a non-conjugated six-membered ring. The carbon atoms on the six-membered ring are sp3 hybridized, and two side chains can be introduced.
The terminal A unit uses the ICIN-2F unit developed by Xu Qiu and others.
This material was developed by Li Dan's research group at the National Center for Nano Science and Technology.
They successively reported two systems, namely the binary PCE10: COi8DFIC system, and the ternary PCE10: COi8DFIC: PCBM system, with device efficiencies of 12.16% and 12.77%, respectively.
Both articles were published in the journal Sci.Bull., which is a journal recommended by the nation as mentioned earlier.
Xu Qiu speculated that they published their work here, which may have contributed to the completion of the above tasks.
Of course, they can be regarded as a wave of bonuses, and Sci.Bull. Behind it becomes a comprehensive category.
Moreover, these two articles are very short, and the format of their publication is Short Newsletter.
Originally, compared to the normal Article format, the article is short enough, usually about three thousand words, three to five pictures.
Now this one is even more exaggerated. The text is only two and a half pages. The full text is a picture, integrating molecular structure, light absorption spectrum, fluorescence spectrum, J-V characteristic curve and EQE curve.
However, the workload of the experiment is not too much, because other characterization tests are also done, including light source GIWAXS, electron microscope TEM, AFM, charge mobility SCLC, but it is included in the supporting information, which contains enough Full 20 pictures.
Of course, the article is not short, and it doesn't matter to Xu Qiu.
He mainly paid attention to three points, that is, the COi8DFIC system has the characteristics of "ultra-narrow band gap", "high current density", and "insensitive to film thickness".
The band gap of COi8DFIC is only 1.26 eV, and the light absorption band edge can reach 1000 nanometers, which is already close to the band gap of silicon. The band gap of intrinsic semiconductor silicon at room temperature is 1.12 eV.
Therefore, the device based on the COi8DFIC binary system has a short-circuit current density of as high as 26 mA per square centimeter, and the ternary system has reached 28 mA per square centimeter, which is higher than the Y series receptors that Xu Qiu has at this stage. exaggeration.
Of course, the high short-circuit current density also comes at a price, that is, the open circuit voltage is low, only 0.68 volts.
Otherwise, if this current density is matched with an open circuit voltage of 0.8 volts or more, the research group that breaks the current world record is not Xu Qiu, but Li Dan's research group.
At the same time, COi8DFIC also takes into account the advantages of the IDIC series. When preparing thick film devices, the attenuation of device performance is relatively small.
Therefore, Xu Qiu preliminarily judged that this material may be a superior alternative to near-infrared receptor materials such as -4F, and it is worth trying.
Sunday.
Because of working overtime on Saturday, Xu Qiu slept until noon before waking up.
He took the phone and tried to take a look at the time, but found that WeChat seemed to have been bombed. It was all unread messages, and there was a missed call from Wei Xingsi.
No wonder Xu Qiu always feels the surrounding vibrates in his sleep. It turns out that it is not an illusion, but the phone is shaking.
He first glanced at the call log of Teacher Wei. It was at 9 o'clock in the morning, and hung up after 7 rings, and there was no second call.
Normally, in this case, it is not a matter of importance. It may just be that Wei Xingsi suddenly had a scientific research idea and wanted to share it with Xu Qiu.
As a result, Xu Qiu didn't call back, anyway, he would meet in the afternoon, and he could communicate with him face to face on everything.
Most of the WeChat messages come from graduate students on campus, including Tao Yan, Mu Xue, etc., as well as Mo Wenlin and Han Jiaying in the research group. In addition, there are even a few old classmates who have not been in contact for a long time. Also sent a message.
Xu Qiu randomly clicked on the top few messages to check, and found that they were all talking about the same thing, and attached a link to forward it.
The link is a tweet from the Onion Club of Modu Comprehensive University: "The legendary direct Ph.D student who has collected more than 30 SCI articles in a year has disclosed the secret of his success. The truth turned out to be..."
Seeing this title, Xu Qiu had already guessed that he should be the protagonist, and it was probably the matter of Tuesday's conference that was further fermented.
Xu Qiu knew a little bit about the Onion Club in the school. He encountered it when recruiting new members of the "Hundred Regiments War", but he didn't pay much attention to it. He just knew that its name was based on Onion News.
Onion News is an organization that provides satirical news in the beautiful country. It is characterized by reporting satirical articles. The content of the articles involves domestic and foreign news as well as local news. It also has entertainment newspapers and websites under its umbrella.
The news provided by Onion News is usually fake news that is fabricated based on real news events.
Although many of the stories are fake, they are not made up by a mere idiot. Instead, they use exaggerated imagination to express their perception of the world. It is an alternative social commentary, so many readers follow it.
And it imitates the characteristics of traditional news. All news is reported in the standard of Yonhap News Agency of the beautiful country, which looks quite like that.
Because it was relatively successful, when the circulation of traditional printing media was reduced and the staff was forced to lay off, the sales of Onion did not suffer much.
Xu Qiu opened the link to the article and, as expected, he saw the picture of himself beating Fang Qiu at the conference at first glance, and he hasn't coded it yet...
After reviewing the text, Xu Qiu found that the content was quite normal, and there was not much oil and vinegar in it.
However, I didn't mention too much about the interaction between Xu Qiu and Mu Xue, only one sentence at the end of the article, which was barely echoing the title.
Most of the content is about Xu Qiu’s achievements, including directly receiving a national scholarship as a freshman, publishing a number of high-level articles such as NC, AM, "Joule", and "Nature·Energy", and publishing SCI articles There are more than 30 articles in total, and more than 10 articles in one area of ​​SCI, etc...
In addition, the text also mentions Magic City University many times, stating that "Xu Qiu is an undergraduate student in the Department of Materials Science and Technology of Magic City University, and has a direct PhD in the Department of Materials Science after graduation."
Not only that, Xu Qiu took a close look at the photo that was taken, and the above projection screen also has a very clear Modu Comprehensive University LOGO.
"The title looks like UC's shocking body, but if you look at the text carefully, it looks like a soft article?" Xu Qiu couldn't help thinking: "Probably he was chosen by the school as a model to establish the image of a strong scientific researcher. Raise the visibility of the school?"
This is possible. In addition to their own hard power, colleges and universities also need to promote their soft power through continuous publicity and public opinion.
Maybe someone saw this tweet and planned to go to Qingbei University, but when their brains got hot, they came to Magic City University to chase Xu Qiu's footsteps.
After all, young people are easily impulsive.
Looking at the current posture again, if only a small group in the school is pushing behind the scenes, it is impossible to achieve such a big influence in such a short period of time.
Even old classmates who hadn't seen for many years were blown out.
Xu Qiu checked the news one by one.
Tao Yan came here to claim credit: "Thanks to me, Xu Qiu, you are famous!"
Xu Qiu pondered for a moment and sent Tao Yan a penny red envelope as a "thank you".
Mu Xue posted a tweet link to the Onion Club and added a string of ellipsis "...".
Xu Qiu also replied "...". He was just unintentional at the time, and he did not expect to have such a big impact. Fortunately, this tweet is not gossip-oriented, otherwise it is really not easy to handle.
Mo Wenlin sent a message: "Now the WeChat group and the circle of friends are reposting this Onion Club's tweet, and it has been circulated among college students. I first saw it in our group at Kainan University. of."
Xu Qiu returned a "surprised" emoji, and then went to check WeChat Moments.
Sure enough, now the entire circle of friends will be screened by this article.
Han Jiaying also sent a link and said: "Brother, you are famous again~"
Xu Qiu replied with a "satisfied" emoticon, and secretly said that the loss is not gossip news, otherwise the school girl might be blown up.
In addition, Niu Minmin, an old high school classmate who has not been in contact for many years, also sent a message to inquire about Xu Qiu's situation.
In high school, Niu Minmin, Jingwei, and Xu Qiu, the three of them all entered early because they were two or three years younger than the other classmates who enrolled normally, and their grades were pretty good, so they often played together.
Later, Niu Minmin went to Qingbei University, Jingwei went to Jincheng University, and Xu Qiu went to Modu Comprehensive University. The three places were separated, and there was much less contact.
Later, Niu Minmin was studying for a master's degree at Qingbei University. It seemed that he had a Ph.D. plan to go abroad. Jingwei chose to work in Tianjin, and Xu Qiu went to the school for a direct postgraduate study. The three took a different path.
After finally getting back to the news from everyone, Xu Qiu lay on the bed and ordered a takeaway.
While waiting for the takeaway, he incidentally read the last news of Onion Club:
According to Xinhua News Agency, the news of the merger of Modu University of International Business and Economics and Modu Business School and the renamed "Modu University of Economics and Business" came out, causing a series of chain reactions.
Relevant persons in charge, experts and scholars from major colleges and universities of the Magic City gathered at Xingbake Coffee Shop, Wujiaochang, to discuss the issue of "rebranding with me, starting from a new beginning", and a three-day group school merger and renaming meeting was opened.
The representatives attending this conference came from 47 universities including Mordu University, Mordu Jiaotong University, Tongji University, Mordu University of Finance and Economics, Mordu University of Technology, Mordu University, etc. The representatives of colleges and universities gathered together like a Chinese New Year. .
The first proposal of this meeting is that in order to build a blueprint plan for cooperation between Mordu Finance and all walks of life, Mordu University of Finance and Economics and Mordu Jiaotong University can try to merge.
After the merger, it was renamed, Modu Jiao Cai University.
Regarding the new school name of Jiao Cai University, a conference representative from the Magic Academy of Magic Capital said:
To make money is not to pay money out. The name is unlucky.
Comrade Chen Erxiu, a representative of Mordu Comprehensive University, agreed and suggested that Mordu University of Finance and Economics could consider merging with Mordu Comprehensive University (formerly known as Fudan University) and renamed Mordu Fortune University after the merger.
This opinion was unanimously nodded and praised by the representatives present.
They said that this renaming plan can be regarded as a name change that has been recorded in the annals of history. This move will undoubtedly lead to a tsunami-level shock in the financial circle of the Magic City, and the symbol of the Magic City as a national financial center will be more obvious.
Mordu University of Technology stated that the exchanges between finance and economics colleges and ours are increasing. We may also consider the merger and rename of Mordu Financial University.
This speech also received nodding from the representatives present.
The representative of Mordu University of Finance and Economics said at the meeting that everyone is deeply honored by our school’s love of this representative, but under the guidance of our school motto, "Being virtuous and knowledgeable, economic time", I also hope that everyone present can consider carefully.
Ma Yiduo, a representative of Mordu Code University, proposed that Mordu Polytechnic University has a reason to merge with Tongji University, because after the change of its name to Mordu Jigong University, it is a form of paying tribute to the living Buddha Ji Gong, the eminent monk of the Southern Song Dynasty. The combination of science and theology can effectively inherit the traditional culture of flower growers.
At this time, the rock representative of the Mordu Conservatory of Music took a sip of cappuccino, and said with a white bubble that Mordu Electric Power College could consider merging with our school, and thus could have the opportunity to form Mordu Electric Music University.
Not only is it a new attempt in the history of music, but after the establishment of the school, there is also a chance to get support and guidance from teachers such as June Tian.
In addition, Mordu Maritime University, Mordu Ocean University, and Mordu Customs College have also put forward a proposal to merge the three schools to form Mordu University.
At this time the meeting ended here and the first voting was held.
In the end, with 24 votes in favor, 20 against, and 3 abstentions, the decision to merge Mordu University of Finance and Economics and Mordu Comprehensive University was passed and renamed as Mordu Fortune University.
After reading the last tweet, Xu Qiu felt that compared to this tweet about himself, the last tweet was obviously more "onion-like".
He guessed that he was mostly selected by the mysterious power, otherwise the Onion Club would not publish two articles with such different styles.
When I think of it including the last hot search on Weibo and the hot list, the probability that there is a mysterious force behind it is very high.
Of course, these are all Xu Qiu's guesses, and no one from the school has come to contact him, and it is difficult to say what the situation is.
But at least, this matter didn't harm him, and Xu Qiu didn't care.
Being able to win both fame and fortune is naturally excellent.
Xu Qiu was not upset by the tweets from Onion Club. After all, the focus of scientific research personnel should be on research.
After eating lunch in the dormitory, Xu Qiu packed up the garbage, threw it into the trash can downstairs, and went to Caiyi as usual.
It is said that the magic city will implement a garbage sorting system in the future, and it will not be able to throw garbage at will.
This may also be the general trend.
At the earliest, in the 1990s, flower growers entered a period of rapid urbanization.
Everyone's eyes are focused on urban construction, and they don't pay much attention to issues such as garbage and sewage. Just find a place to store garbage.
However, the urbanization of flower growers was too fast, and people soon discovered that there were piles of garbage around the city.
Not to mention the waste of land, it also affects the environment and directly affects the economic benefits of the city, so the construction of landfills began.
The typical way is to find a suitable ravine in the outer suburbs of the city, do some anti-seepage treatment on the ravine and then dump the garbage in the ravine.
Generally, such a garbage dump has a service life of more than ten to twenty years, but it is often found that the ditch is filled in ten or a little more than ten years, and then the ditch will be closed for greening or other purposes.
But this method in fact only solves the problem of garbage storage. Later leachate, biogas, non-degradable garbage, etc. are all problems, which are a temporary solution rather than a permanent cure.
Moreover, the country's land is limited, and the method of landfill has been used, and one day all the land will be filled.
To solve the problem of urban garbage, the ultimate solution is to classify and dispose of garbage.
At present, the country that has achieved the ultimate in garbage recycling in the world is the neon country.
Each of their residential quarters has several fixed large-scale garbage stations.
The garbage station is a house enclosed by barbed wire, with latches but no locks. People need to sort and bag their own garbage and send it to the recycling station.
Small pieces of garbage such as household garbage and books and newspapers should be placed in their respective rooms.
Large pieces of garbage such as furniture and home appliances are placed outside the house, and garbage tickets must be purchased in advance.
The recycling station is managed by a dedicated person. Before the garbage is transported away, they have to sort out the useful items carefully.
The concept of "garbage needs to be sorted" is almost equivalent to the domestic "cannot spit and urinate" for Neon people.
If you don’t sort the garbage in accordance with the regulations, you will face high fines, and even serious imprisonment of up to five years.
Of course, no system is perfect.
The garbage classification system of Neon Country has also been criticized by many people because it is too complicated and sophisticated, but at least the result is quite good.
If China wants to implement a garbage classification system, it can be foreseen that various problems will definitely arise.
For young people who are more receptive to new things, it may be easier to implement them.
The hardest thing to deal with should be groups like the auntie of the vegetable farm, who have been throwing away trash at will for decades. It is not possible to change their lifestyles in a short while.
Moreover, some aunts have the skills of "you reason with me, and I play rogue with you", which is more difficult to deal with.
When he arrived at Caiyi 216, Xu Qiu greeted everyone.
The other friends in the research group have already learned about Xu Qiu's listing on Onion News, but they are relatively calm.
After all, they were used to getting along with Xu Qiu day and night. After seeing the tweet, their thoughts were roughly: "Why is this person as good as Xu Qiu? Oh, it turns out to be Xu Qiu. That's okay."
Xu Qiu sat down in front of her seat and began to think about how to continue to optimize the performance of laminated devices today.
Although the simulation laboratory has begun to explore, the time in reality cannot be wasted.
At this time, Xu Qiu suddenly remembered that the device efficiency exceeded 15% on Saturday, and he has not notified others.
The school girl happened to go home this Saturday and did not accompany him to do the experiment;
Wei Xingsi was always at 218 on Saturday afternoon. Xu Qiu went to him to get some newly printed documents. At the same time, he discovered that Teacher Wei was watching American dramas on a projector in the office. After dinner, Teacher Wei disappeared;
Senior Sister Wu Feifei also came here on Saturday afternoon 216. She dropped a courier, chatted with Xu Qiu, and left.
And Xu Qiu only got 15.00% efficiency data just after ten o'clock in the evening.
Just as Xu Qiu was thinking about how to announce this result to everyone and make everyone "happy", familiar footsteps sounded in the corridor.
Not long after, Wei Xingsi appeared at the door of 216. As soon as he met, he said to Xu Qiu: "Xu Qiu, how did you do with laminated devices yesterday?"
Last night, Wei Xingsi planned to ask about the situation after Xu Qiu's device was ready, but Fang Guangwu pulled him out for a drink. He didn’t end the meal until more than ten o’clock in the evening, and then he went home and forgot about it. , I just remembered this morning, thinking about calling Xu Qiu to ask about it, but it didn't get through.
"The highest achieved 15.00%, which is just a whole number." Xu Qiu calmly responded.
"!" As soon as the voice fell, everyone looked towards Xu Qiu in unison, paying attention.
Mo Wenlin participated in the optimization process of the laminated device almost all the way, and she was most emotional:
About a month ago, he followed Xu Qiu's idea to prepare laminated devices. At first, he could only achieve about 10%, but now it is 15%.
You know, the upper limit of efficiency in the organic photovoltaic field over the years has not risen by 1% in a year, and the average annual increase is almost 0.5%.
This 0.5% is still the result of the joint efforts of all research groups in related fields around the world.
And now in just one year, the upper limit of the efficiency in the organic photovoltaic field has broken from 12% to 15%.
The 3 percentage point leap is almost all the credit of Xu Qiu alone.
Moreover, looking at this momentum, 15% can't stop Xu Qiu's footsteps.
Wei Xingsi was also shocked. On Friday, Xu Qiu told him that he had achieved 14.5%. At that time, he was thinking: "Looking at this posture, in one month, it is estimated that the efficiency will increase by 0.5% and reach 15%. threshold."
Unexpectedly, it only took a day to break through.
Originally, Wei Xingsi thought he had looked at Xu Qiu high enough, but he didn't expect to think Xu Qiu was too simple.
The previous law of efficiency increase in the organic photovoltaic field is not established by Xu Qiu.
Maybe 16% next month?
He seemed to really see a piece of "Nature" beckoning to him.
Wei Xingsi has experienced a lot of strong winds and waves over the years. Although his inner activities are very rich, his face does not show any gaffe, but his tone is still slightly agitated, and he asked: "Is the device structure picture ready?"
Xu Qiu shook his head: "I haven't had time to draw a picture, let me draw one on the spot with a pen."
As soon as he finished speaking, Han Jiaying tacitly handed over an experiment notebook and a pen.
Xu Qiu took the pen and paper and turned to a new page on the experimental log. While drawing the device structure, he explained: "In the device structure adopted by the optimal system, the effective layer of the bottom battery is the ternary J4:PCBM:IDIC -4F system, the effective layer of the top cell is the binary PCE10:-4F system, and the middle transmission layer is zinc oxide, M-PEDOT..."
Subsequently, Xu Qiu repeated the method for further optimization of stacked devices that he thought of before: "The next optimization direction is mainly in terms of materials. I intend to use materials from other research groups simultaneously, including the Li Dan project of the National Center for Nano Science and Technology. The COi8DFIC developed by the group......"
Wei Xingsi nodded repeatedly. Originally, he wanted to make some suggestions, but after thinking about it for a long time, it seemed that there was nothing to add. Xu Qiu's optimization route and logic were very smooth.
Therefore, Wei Xingsi did not force Xu Qiu to increase the difficulty, saying: "Yes, just follow the current thinking... By the way, the COi8DFIC material, it is best to synthesize it by ourselves, or find a channel to buy it."
In fact, with the current influence of Wei Xingsi, it is possible to ask for some COi8DFIC materials from Li Dan's research group, but the cost of the short hand is that the article has to be named by the other party, and if it is synthesized or purchased commercially. The material does not need to be named, only the corresponding literature needs to be cited.
"I understand," Xu Qiu added: "COi8DFIC is probably not available. This material has just come out, and it is relatively small. We need to synthesize it ourselves."
"Hmm..." Wei Xing thought for a while and said, "Well, Wu Shengnan, can you help synthesize COi8DFIC?"
"Okay, no problem." Wu Shengnan agreed very quickly.
Xu Qiu still doesn't know whether COi8DFIC is good or not. The simulation laboratory is still synthesizing. UU reading www.uukanshu.com did not get the materials. If the final result is not good, it will waste a lot of Wu Shengnan's time.
However, since the post-doctorate sister has no objections, there is no need for him to object.
And Wu Shengnan's idea is very simple, now there is an opportunity for a CNS second or third CNS story in front of her, should you cherish it? Of course it does.
In Xu Qiu's previous article "Nature·Energy", she only mixed one four works because of insufficient contributions. If this contribution is enough, mixing two works would be very cool.
For the top issue of CNS, even the second work is a great honor.
Like other journals, there is not much mention of the second work, but a second work of "Nature" also has a certain face when it is taken out.
Mo Wenlin's contribution to the current stacking work is not small. What she is doing now is to compete with Mo Wenlin for this second work.
PS: Eight thousand words update, put a bowl to ask for a monthly pass...
I have a list of chapters of the scientific research assistance system