I Have a Research Support System

Xu Qiu continued to read the literature sent by Wei Xingsi.

The third area one article comes from Li Dan of the National Center for Nanoscale Science and Technology, and their research group published another Sci. Bull., which is also a "short communication" article with only one picture.

Speaking of which, Xu Qiu told Wei Xingsi about the journal Sci. Bull. It was not in Mr. Wei's journal retrieval database before.

In addition, if the title of this journal is abbreviated into two letters, it can compete with the abbreviation NC of "Nature Communication"...

Li Dan's research group reported a ternary conjugated copolymer donor material named S1.

The molecular structure of this material is modified on the basis of the PBDB-T benchmark donor. PBDB-T is a D-A binary copolymer, the D unit is BDT, and the A unit is BDD.

In the case of S1, the second A unit is additionally introduced, that is, a thiophene unit substituted with fluorine atoms and ethyl acetate. This thiophene unit connected with two electron-withdrawing groups can reduce the HOMO energy level of the donor material.

Fine tuning of the energy level structure of the donor material can be achieved by changing the ratio of the two A units in the ternary conjugated copolymer molecule.

The results show that the device performance of the donor material obtained by introducing 10% mole fraction of the second A unit is the best.

At this time, the S1 material was combined with the COi8DFIC receptor they developed before, and the battery device prepared had a maximum efficiency of 13.36%.

This is a system whose efficiency is closest to Xu Qiu's "Nature Energy" article among the binary single-junction organic photovoltaic devices reported so far.

Therefore, Xu Qiu also included the S1 material in his donor material library.

In fact, Xu Qiu was quite impressed with Li Dan's research group.

The articles published by the other party are basically on Sci. Bull. Most of them are very short "short communication" articles, and they are all relatively efficient systems.

In addition, Xu Qiu has never heard of Li Dan in the field of organic photovoltaics before. He speculates that the other party may have switched from other photovoltaic fields, and then just caught the non-fullerene trend and took off directly.

Of course, it is also possible that the journals submitted by the other party are relatively "biased", and they are not in Wei Xingsi's journal library, so they cannot be seen by Xu Qiu.

The fourth work is an AM article from Ma Weiwei's research group.

What they are doing is ITIC-based polymer acceptor materials. The main idea is what Xu Qiu told them in the review of "Joule" and the exchange conference.

However, the device performance they reported is not high, and the efficiency has just exceeded 10%.

Maybe it's because their device optimization is not very good, Xu Qiu's results of the same system in the simulation laboratory, the efficiency can reach more than 11%.

This job was able to be published on AM. On the one hand, they may be lucky. On the other hand, it may be because this job is relatively new. After all, it has created a small segmented field.

In addition, it may also be related to the names of Xu Qiu and Wei Xingsi in this article.

There are four authors in this AM article, Ma Weiwei is the fourth author plus communication, her master student is the first author, Xu Qiu is the second author, and Wei Xingsi is the third author.

Among them, Xu Qiu did not participate in the specific experiment of this work, but only helped the other party to make changes before submitting the manuscript.

However, the idea of ​​the experiment was proposed by Xu Qiu, so it is not too much for him to hang up a second work.

Moreover, this is also the rule of the game in the scientific research circle, everyone carries the sedan chair.

Like an academic leader, there are hundreds of articles at every turn, and nearly a thousand articles, many of which are posted by name. It is difficult to publish so many articles with only one research group.

Even for a large research group, it is very rare to be able to publish 20 large and small articles in a year.

In most cases, the big boss actively or passively cooperates with other people. The big boss proposes an idea and makes a name for it. Others help realize this idea, and finally achieve a win-win situation.

The fifth work is from Yan Hu of Hong Kong University. They published a sub-journal of AM, AEM.

Based on the derivatives of the PCE11 donor, Yan Hu's research group synthesized a PBT3T donor molecule similar to that made by Xu Qiu before, and named it PffBX-T3.

After that, they combined the PffBX-T3 donor material with the ITIC2 acceptor material to prepare an organic photovoltaic device with an efficiency of 11.3%.

This work is not very bright, it is based on the modification of the donor material, so it was only published on AEM.

Now the threshold in the field of organic photovoltaics has been raised very high by Xu Qiu.

Originally, the efficiency of 8% was able to get into the second district and the weaker district. Now if there is not enough novelty, it needs 10% efficiency to be admitted to the weaker district. The efficiency of 11% can only publish AM sub-journals.

Of course, this is the standard for pure efficiency work.

If there are other bright spots, such as Ma Weiwei's article, although the efficiency is not as good, it can also be posted on AM.

For the sixth work, Lu Changjun's research group from the Institute of Chemistry, Chinese Academy of Sciences published a JACS.

They reported an organic photovoltaic stack device with an efficiency of 13.8%.

Most of the materials used are old materials, the bottom battery is PBDB-T:ITCC-M, the top battery is PCE10:IEICO, and the transmission layer materials use zinc oxide, PEDOT:PSS, PCP-Na, PFN-Br.

Previously, the Forrest research group of the beautiful country also published an article on stacked devices in the field of organic photovoltaics, but in "Nature Photoelectricity", the efficiency can reach more than 14%.

In fact, in terms of the level of these two multilayer device articles, there is not much difference between the JACS of Lu Changjun's research group and the previous "Nature Optoelectronics" of Forrest's research group.

But Lu Changjun and the others only published one JACS, which is a pity.

There may be many reasons. For example, Lu Changjun and his team are a bit slow in their shooting speed, and the submission time is later than that of the beautiful country Forrest research group; the efficiency has not broken through, and the value of 13.8% is slightly lower than the 14%+ of the Forrest research group; The influence of organic photovoltaic field is not as good as Forrest.

In summary, only one JACS was published.

In addition, it may also be because there is no transitional journal between a top journal like JACS and a major sub-journal of Nature like "Nature Optoelectronics".

If you can't make it to the major sub-journals of "Nature", you can only fall back to JACS, AM, NC, EES... .

Therefore, some research groups will not submit to the major sub-journals of "Nature" if they feel that they can't get ahead, because the major sub-journals of "Nature" are relatively slow in reviewing manuscripts, which is too time-consuming.

The seventh piece of work, Choi's research group published an ACSEL.

They synthesized a donor material named 3MT-Th. The molecular structure of this binary D-A copolymer donor material is very simple. The D unit is BDT, and the A unit is thiophene substituted with ethyl acetate. Easier and probably less expensive.

They combined 3MT-Th donor and IDIC acceptor materials, and used the non-halogen solvent toluene for device processing, and the efficiency can reach up to 10%.

Generally speaking, the design idea of ​​this 3MT-Th material is somewhat similar to the PTQ series materials that Xu Qiu gave to the school girls before.

It mainly highlights the highlights of "simple synthesis and cost saving". In addition, this work also brings in the concept of "non-halogen solvent".

Inspired by this article, Xu Qiu plans to let the juniors try non-halogen solvents in the future. Although the efficiency of the device may not be improved, it can be regarded as a bright spot picked up for nothing.

Seeing this, Xu Qiu found that most of the newly reported articles were based on the synthesis and development of donor materials.

He speculates that it may be because he has made too many acceptor materials, which has almost taken the path that other people can walk, causing others to choose the path of donor materials.

Of course, it may also be because the dominant direction of many research groups is the direction of the donor.

After all, in the previous era dominated by the fullerene system, the development of acceptor materials was thankless, so most researchers were engaged in the development of donor materials.

In addition, from a utilitarian point of view, Xu Qiu has already developed the receptor material very well.

However, donor materials are relatively scarce, and there are many opportunities.

As long as a similar donor material is synthesized by the way, and mixed with the purchased ITIC and other benchmark acceptor materials, it is not difficult to obtain a 10% efficiency.

Once the efficiency can reach 10%, you can basically publish an article in the weaker area, or even the first area.

Articles of this level are very attractive even to full professors.

At the same time, Xu Qiu also found that the scientific research sense and reaction speed of domestic colleagues are relatively fast.

Looking around, more than half of the organic photovoltaic field is occupied by domestic researchers.

Of course, this may also be related to the reduction of research funding in the field of organic photovoltaics in the beautiful country.

Including Wei Xingsi's return from the beautiful country, which was actually affected by the policy of the beautiful country. He had some problems in the operation of the NREL research group.

There are only these seven articles in the first district, and the rest are small articles that are weak in the first or second district.

Now when Xu Qiu reads these small articles in the weaker districts one or two, as long as they are not purely related to the mechanism, most of the articles can be read in less than a minute.

Just look at the title, abstract, and glance at the chart, and you can basically know what kind of work the other party has done.

Back and forth just a few things: donor-based modification, acceptor modification, transport layer modification, or playing around with some other concepts.

It looks like there is some water, but as a practitioner, Xu Qiu also knows that there is nothing to do about it.

At this stage, there really isn't much new stuff to discover in the field of organic photovoltaics.

To put it bluntly, the field of organic photovoltaics is still in the development stage, and we can only simply compete for efficiency. High-efficiency journals go to the top journals, and low-efficiency journals without too many bright spots go to inferior journals.

Only when the efficiency reaches a certain level can we consider more far-reaching issues.

Just like, people will pursue spiritual satisfaction when they are full.

Now the field of organic photovoltaic is still in a state of starvation. If the efficiency cannot be broken through, the final result is to die out, that is, to starve to death.

Only when you are full, for example, if the efficiency exceeds 18% or 20%, can you compete with perovskite and silicon-based solar cells, then you can consider building a theoretical model to solve various problems that may be encountered in industrialization.

This is a gradual process.

It is almost impossible to achieve a sudden breakthrough overnight.

This is not only the case in the field of organic photovoltaics, but also in other scientific research fields, even popular scientific research fields.

Because of the development of science and technology, the areas that are easy to make breakthroughs have basically already been broken through, and most of the rest are hard nuts to crack.

Some people say: "Perovskite and graphene, the two major fields have supported many researchers", "Doping graphene with bird droppings can make its performance better."

The implication is: "These two fields are easy to water articles, but also water a lot of articles."

There is indeed some truth to what they say.

It can be seen that many CNS articles are published in these two fields every year, and there are countless top journals such as AM and JACS.

For example, Cao has published 7 papers in "Nature" to study graphene.

But at present, whether it is perovskite or graphene, they are still in the laboratory stage and cannot be industrialized.

In this sense, it is indeed quite watery.

So many top journals have been published, so many scientific research resources have been occupied, but there is no actual output.

But on the other hand, if people don't go to water articles, then these two fields with great potential will not be able to develop.

Behind the "water" is actually that the era of the technological explosion has passed, and the scientific and technological progress of human civilization has stagnated, or the situation of low-speed development.

The technology tree that originally required 100 points to light up may now require 100W points to light up.

In this case, even if the total ability value of scientific research practitioners has increased with the development of civilization, for example, it has increased by 100 times, but the time it takes to light up the technology tree is still 100 times that of the original.

In other words, "water" is only an external manifestation of slow development.

In fact, if you think about it in another way, you can know that whether it is domestic or international, scientists who stand at the top are most likely to pursue scientific research. If they are really capable of making key breakthroughs, who will I want to go to the water article.

After reading the documents sent by Mr. Wei, Xu Qiu went to the wos website to check some of his own work. Now that it is February, the information of the articles should be updated once.

It turned out that the AM article given by PCE11, which is Xu Qiu’s first Grand Slam article, has now lost the small flame logo of the hot article, but still retains the small crown of high citations.

This is also normal. After all, the PCE11 material is too crystalline, and its compatibility with fullerene receptors is not bad, but its compatibility with most non-fullerene systems is not high.

But now the times have changed, the nearly 20-year dominance of fullerenes in the field of organic photovoltaics has come to an end, and PCE11 has become the "tear of the times".

AM articles, hot articles and highly cited marks of ITIC receptors all exist, and the number of citations has successfully exceeded 100 times, reaching 168 times, and the number of citations has increased very fast.

This is mainly due to the recent explosion of non-fullerene-related articles. In the first and second sections of SCI alone, nearly 30 articles were published in this month. Articles, this number will only be higher, and may exceed 50 articles.

Most of the published articles in the field of organic photovoltaics are related to ITIC, so they will basically cite the earliest ITIC articles published by Xu Qiu.

In addition, the ITIC-related "Joule" review, and the IDIC-4F receptor's "Nature·Energy" article were rated as hot articles and highly cited articles, and obtained the small flame and small crown logos.

At the same time, the real-time citations of these two articles both exceeded double digits, and the growth rate was also very fast.

This is all expected. Now that Xu Qiu and Wei Xingsi have become leaders in the field of organic photovoltaics, the possibility of their published articles being paid attention to and cited by other research groups is very high.

Even if other authors only consider it from a utilitarian point of view, if they don't quote Xu Qiu's article when posting an article, it will be embarrassing if the article is sent to Wei Xingsi during the review...

After all, the opinions of different reviewers are also different on the side of the journal editor. For example, if Wei Xingsi's research group reviews manuscripts in the field of organic photovoltaics, if he gives a rejection opinion, basically the article will be ignored.

After saving a few screenshots of the newly released Little Flame and Little Crown, Xu Qiu closed the wos webpage.

A few days later, a very big piece of good news came from the simulation laboratory.

That is, after a series of side chain regulation, three binary single-knot systems with an efficiency exceeding 17% were finally born.

The names of the corresponding acceptor materials are Y15, Y18 and Y20, and the devices prepared by combining them with the J4 donor material have the highest efficiencies of 17.17%, 17.02% and 17.40% respectively!

The efficiency of the best system J4:Y20 even surpassed the highest efficiency of 17.36% for stacked devices in the previous "Science" article!

Specifically, Y15, Y18, and Y20 are all materials obtained by regulating the side chain of Y14.

In the initial Y14 material, the side chain on the TT unit is straight-chain undecyl (C11), which is a straight-chain saturated alkane with eleven carbon atoms, and the side chain on the nitrogen atom is 2-ethylhexyl ( EH), that is, branched chain saturated alkanes with 8 carbon atoms.

First, the Y15 material.

Compared with the Y14 material, it only changes the side chain on the TT unit to a straight-chain nonyl group (C9), which is a saturated alkane with nine carbon atoms, and the side chain on the nitrogen atom keeps EH unchanged.

The device performance of the Y15 system has been slightly improved. After a simple analysis, Xu Qiu attributed it to "shortening the side chain makes it easier to realize the stacking of acceptor molecules, thereby improving the charge mobility of the material."

Of course, the actual influencing factors are more complicated, which is a balanced result under the joint influence of multiple factors.

For example, Xu Qiu also synthesized the Y16 material. Compared with the Y15 material, it further reduces the side chain on the TT unit and changes it to a straight-chain heptyl group (C7), which is a saturated alkane with seven carbon atoms. The side chain of EH remains unchanged.

The device performance after blending Y16 and J4 materials is only 12.68%.

Compared with the 16% efficiency of the Y14 system and the 17% efficiency of the Y15 system, the efficiency of the Y16 system has dropped significantly.

The reason why the performance of Y16 has shrunk, on the one hand, may be that the side chain is too short, which makes it difficult to guarantee the solubility of the material. For example, Y14 and Y15 can prepare a 15 mg/ml chlorobenzene solution at room temperature, while Y16 needs to be heated to 80 degrees Celsius. Above, the solution with the same concentration can be prepared;

On the other hand, it may be that the side chains are too short, resulting in too easy molecular stacking. In the GIWAXS results, the crystallization signal of the Y16 material is obviously stronger than that of Y14 and Y15, which makes the crystallinity of the Y16 material too strong to be compared with J4. The bulk materials can be effectively blended, but the blended morphology is poor.

Secondly, Y18 material.

Compared with the Y14 material, it only changes the side chain on the nitrogen atom to 2-butyloctyl (BO), which is a branched saturated alkane with 12 carbon atoms, and the side chain on the TT unit Leave C11 unchanged.

The DFT simulation analysis results show that the molecular skeleton of the Y14 material has a twist angle of 15 degrees, and the coplanarity is poor, while the twist angle of the molecular skeleton of the Y18 material is only 5 degrees.

Therefore, Xu Qiu attributed the improvement of the performance of the Y18 material to "the relatively large steric hindrance of the EH side chain on the TT unit of the Y14 material, which makes the coplanarity of the Y14 molecular skeleton poor and affects its charge transport performance."

Finally, the Y20 material.

It combines the advantages of Y15 and Y18, not only changing the side chain on the TT unit to a straight nonyl group (C9), but also changing the side chain on the nitrogen atom to 2-butyloctyl (BO).

Finally, the Y20 material showed a breakthrough in device performance, and the result of 1+1\u003e1.

In addition to Y15, Y18, and Y20 that have successfully entered the 17% club, there are some other "failed" Y-series materials, such as the Y16 material just now, which directly fell to 12%.

This also shows that the careful regulation of side chains is still very critical to the final device performance of Y-series materials.

From this point of view, the regulation process of the Y series materials is very similar to the regulation of the original PCE11 materials, and they are also mainly aimed at the regulation of the side chain.

Xu Qiu suddenly found a reason to reasonably self-cite the PCE11 AM article.

To be honest, Xu Qiu was a little surprised that the exploration of Y-series receptor materials went so smoothly during the Chinese New Year.

Thinking about it, he developed the Y3 material, which achieved an efficiency of 14.8%, but he wanted to break through to 15%, just like constipation, and he couldn’t get up after a long time.

But now, since the Y12 was developed, in just half a month, the efficiency has directly increased from 15% to 17%.

However, it is also understandable.

Scientific research is the same as diarrhea. As long as you find the key point and come out at the first moment, it will be much smoother later, just like "inspiration gushes out".

Of course, just like the rareness will always be finished, there is a limit to the improvement.

For example, it is relatively difficult to break through this 17.40% to 18% or even higher now.

Fortunately, Xu Qiu still has a lot of cards in his hands.

In the process of exploring the Y series materials, for the convenience of comparison, he has always locked the donor material as J4.

Now, he has enriched his donor library through literature reading, and there are many other donor materials to choose from.

Including the L2, L6, and S1 materials obtained from Zang Chaojun of Qingbei University, Lu Changjun of the Institute of Chemistry of the Chinese Academy of Sciences, and Li Dan of the National Nano Science and Technology Center, Xu Qiu has simultaneously developed their current materials and newer materials. Version.

This approach is a bit like the approach of Nanshan Pizza Hut.

For example, the Happy Farm developed by Happy.com was about to make a profit. As a result, Nanshan Pizza Hut also developed a Nanshan Farm, which was directly free of charge, and then killed Happy Farm.

However, in scientific research, everyone is for the progress of the entire field, and it is very normal to learn from each other's achievements.

The paper is published for others to refer to, otherwise why publish it.

Moreover, although Xu Qiu made some modifications on the basis of L2, L6, and S1, such as introducing fluorine atoms, chlorine atoms, etc., he did not make a major change in the name of the material, but directly called it L2-Cl, L6 -F and so on, it is more face to the original author.

Therefore, the next point of exploration is to use these new materials to arrange and combine with Y15, Y18 and Y20.

In addition, regarding the processing technology, Xu Qiu also has various means of fine optimization, including solvent additives, thermal annealing, solvent annealing, vacuum placement, thermal spin coating, spray coating...

So many methods have been developed, and now there is always one that can be used.

In short, the goal is to hit 18%!