I Have a Research Support System

After entrusting Tian Qing to Xu Qiu, Wei Xingsi continued: "If the experimental results of the exciton diffusion distance are consistent with Xu Qiu's previous conjecture, there is hope for a big article...Let me think about it, now How efficient is the IDIC system?"

"So far, the efficiency is about 11.6%," Xu Qiu paused, and said, "I have asked Wu Shengnan to synthesize IDIC-4F and IDIC-M. These two new systems may achieve further breakthroughs in efficiency."

"Okay," Wei Xingsi nodded, "When the time comes, find a high-efficiency system from those two materials that can maintain a relatively small HOMO energy level difference with the donor material, and then ask Feng Shengdong to make a TAS..."

Wei Xingsi continued: "For the light source, the GIWAXS test will be in September. What about the other resonant soft X-ray scattering (R-SoXS), when can it be tested?"

Xu Qiu responded: "For R-SoXS, this time I plan to wait for them to go to work and apply for an emergency flight time. As for the application materials for R-SoXS' normal flight time in September, I have already asked Mo Wenlin to write them, but Even if you pass the review, you will not be able to have a formal opportunity until next year."

"That's fine," Wei Xingsi added: "When the time comes, don't forget to do the NIM test."

Xu Qiu nodded. On the whole, Teacher Wei's idea is basically the same as his, which is to integrate multiple highlights into one big article.

It’s just that Xu Qiu doesn’t know what journal Mr. Wei plans to submit to. Of course, this is also because of the different perspectives of the two. He knows that the efficiency of the new system must break 13%, but Mr. Wei doesn’t know, so it’s normal that the other party doesn’t make a high profile now. .

When it comes to submitting articles, Wei Xingsi is usually more conservative, and he doesn't want to revise or resubmit repeatedly.

Han Jiaying's NC article has been submitted last week, and she briefly reported the progress of the experiment: "J2 and J3 have been synthesized, but the performance has not yet come and tested."

Wei Xingsi nodded: "Okay, hurry up and test this week."

Han Jiaying continued: "By the way, Xu Qiu also arranged for me to work on the ITIC-Th system."

Wei Xingsi wasn't too surprised: "Yes, you can discuss the specific allocation by yourself."

Wu Shengnan was mainly doing synthesis last week, so he didn't prepare PPT. Oral report:

"Because I helped Xu Qiu synthesize IDIC-4F and IDIC-M last week, the original plan to modify the central D unit to synthesize 4TIC, IHIC and other systems has been temporarily put on hold..."

"The IDIC-4F and IDIC-M haven't been synthesized yet, but they should be available tomorrow or the day after tomorrow..."

"In addition, Xu Qiu also asked me to be responsible for the work of m-ITIC, and the four-in-one work of IT-M, IT-2F, IT-2Cl and IT-4Cl."

Wei Xingsi gave a "hmm", and then looked back at Xu Qiu in some surprise. ‘Very courageous, a total of six systems were synthesized, four jobs were sent out, and three articles were sent out, leaving only one IDIC. '

Wei Xingsi put himself in Xu Qiu's position, thinking that he would not hand over so much work to others, and then leave only one article for himself. Maybe this is the difference between the two. What I have to admit now is that Xu Qiu's single opinion The ability to produce scientific research results has actually surpassed itself.

Finally, Mo Wenlin made a closing report:

"Last week I conducted device testing and basic characterization of two ternary blend systems, H22:ITIC:IEICO and J1:ITIC:PDI4-B4T, and the results showed that..."

"At the same time, I also produced several ternary system ideas, including J2:IDIC-4F:IEICO-4F..."

Mo Wenlin eloquently listed more than ten kinds of ternary systems. After all, ternary is just a matter of luck, and there will be no problem if you try more.

Anyway, there is not much difficulty in the experimental operation. You only need to prepare all the solutions first, and then apply each solution to two devices to test the water. If the efficiency is surprising, then conduct in-depth research. If the performance is mediocre, then discard the system directly, or give it another chance.

The group meeting is over, and the few articles submitted before the holiday, except for the one that Duan Yun was rejected, there is no news about any of them now, but counting the time, it should be back soon, just in these few weeks.

In the afternoon, Xu Qiu arranged for Mo Wenlin to take Tian Qing to test the exciton binding energy. He randomly gave them an IT-4F system as an introduction. The exciton binding energy, exciton diffusion distance and other properties of new donor or acceptor materials are found out, and a set of databases is constructed.

In fact, the current structure of the organic photovoltaic field in the group is close to the model of a large research group, that is, a clear division of labor and cooperation. In the beginning, like Wu Feifei, Chen Wanqing, Tian Qing, and Duan Yun, the four research directions were for each of them.

Han Jiaying started to prepare devices and explored the properties of J2 and J3 materials. Chen Wanqing continued to paddle and write papers. Wu Shengnan went to Zhangjiang to do synthesis. Now the synthesis of non-fullerene acceptor materials is mainly entrusted to her.

Xu Qiu is going to perform data processing and fitting of the ITIC exciton diffusion distance. Before that, he needs to confirm the film thickness of the sample.

The premise of inferring the thickness from the absorbance of the sample before is that the thickness of the sample at a certain absorbance is known, and the film is all on the scale of a few nanometers, tens of nanometers, or a hundred nanometers, and it is impossible to measure the thickness with a ruler.

The method Xu Qiu intends to use is scanning electron microscopy (SEM), which is a commonly used method to confirm the thickness of samples at the micro-nano level.

The principle of SEM thickness measurement is to scan the fracture surface of the sample and read the thickness information directly. The specific experimental method is to first spin-coat the sample on a glass sheet, then use a glass knife to cut the substrate from the middle, then break it off, and finally use SEM scanning and photographing.

Of course, this method is also limited.

If this method is used to test a film of 100 nanometers, it is not a big problem, but if it is a film of several nanometers, it is relatively difficult, because it basically reaches the resolution limit of the SEM, especially the SEM on the first floor. It is still an early product that is about to be eliminated, and the resolution is even worse.

Therefore, Xu Qiu deliberately applied two thick "films" of ITIC and IDIC. Among them, IDIC is a precautionary measure. Although it may not be used today, it will definitely be used in the future.

According to the concentration and rotational speed of the spin-coating solution, Xu Qiu preliminarily estimated that the film thickness of both should exceed 100 nanometers. Anyway, it is not preparing devices now, as long as the film is uniform.

The SEM test was successfully completed.

In the evening, Xu Qiu got the final fitting result, and the exciton diffusion distance of ITIC is 14.4 nanometers.

This result is more in line with his expectations and is an expected result.

According to literature reports, the exciton diffusion distance of the standard P3HT material is about 10 nanometers, and the ITIC system cannot prepare thick-film and large-scale devices, so its exciton diffusion distance is comparable to that of traditional polymer donor material systems, and it is easy to understand .

On Tuesday, Xu Qiu continued to test the exciton diffusion distance of the IDIC system. The final fitting result showed that the exciton diffusion distance of IDIC was 16.8 nanometers.

This is an unexpected result.

IDIC and ITIC, the exciton diffusion distances are 16.8 and 14.4 nanometers respectively. Although there is a gap between the two, it is only about 17%. This gap is not enough to fully explain why the IDIC system can produce large-sized, thick-film devices. And another ITIC system cannot.

Xu Qiu analyzed two possibilities:

First, there may be problems in the previous inference process, which needs to be demonstrated again; second, the experimental data obtained from 90 data points is not enough, and the error of the fitting result is relatively high.

The former is easy to understand, and the latter is because the data fluctuates during the experiment, and sometimes there will be some abnormal data points, or "singular points".

If the singular point is not discarded, the final fitting result is likely to deviate greatly from the actual result, but if the singular point is discarded, how to define the singular point is a problem, and the subjective component is very large.

In other words, there is a lot of room for manipulation in the process of data fitting, and sometimes you can fit any data you really want.

For example, a set of numbers, 10, 15, 20, 25, 30, the average value is 20. If 10 is considered as the singular point and discarded, the average value of the remaining four data will change to 22.5.

In the linear fitting, this kind of operation has relatively little influence on the results, but now the fitting of the exciton diffusion distance is nonlinear. If a few "singular points" that are not so "singular" are forcibly removed, the IDIC system will eventually The fitted result of 16.8 nanometers can be changed to 26.8 nanometers.

Of course, Xu Qiu only suspected that there was an error in the fitting result. If the real result was what he tested, he would definitely not carry out the "operation".

Because once this kind of thing starts, there is no turning back, and we can only continue to weave lies, using one lie to whitewash another lie.

Anyway, even if the reason why the IDIC system can produce thick films cannot be analyzed, it is better to report the real situation.

Just be honest and say, "We've discovered a unique experimental phenomenon that can't be explained right now," and leave the question to other researchers, or your future self, to figure it out.

After setting the keynote, Xu Qiu handed over the ITIC and IDIC exciton diffusion distance test experiments to the simulation laboratory for a large number of repetitions.

On Wednesday morning, Xu Qiu received the results of the mock lab test.

After fitting hundreds of experimental data, the final results show that the exciton diffusion distances of ITIC and IDIC are 13.0 nm and 19.2 nm, respectively.

From this point of view, there is indeed a certain error in the previous fitting results due to insufficient data.

Moreover, with one increase and one decrease, the numerical results of the exciton diffusion distance of ITIC and IDIC have been widened by about 48%, which is not small.

Therefore, the previous conclusion can be retained, and it is considered that the increase in the exciton diffusion distance is one of the main reasons for "the device performance is not sensitive to thickness and size".