Chapter 361: Unexpected

After entrusting Tian Qing to Xu Qiu, Wei Xingsi continued: "If the experimental results of 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, "At that time, find a high-efficiency system that can maintain a relatively small HOMO energy level difference with the donor material from those two materials, and then let Feng Shengdong do a TAS..."
Wei Xingsi continued: "On the light source side, the GIWAXS test is in September, right? Another resonance 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 apply for an emergency flight time after they go to work. As for the application materials for the normal flight time of R-SoXS in September, I have asked Mo Wenlin to write it, but Even if the review is passed, there will be no formal opportunity until next year."
"That's OK," Wei Xingsi added one more point: "When that happens, don't forget to do NIM testing."
Xu Qiu nodded. On the whole, Mr. Wei's idea is basically the same as that of him, which is to integrate multiple highlights to make a big article together.
It’s just that Xu Qiu doesn’t know what journal Wei is planning to vote for. Of course, this is because the two people’s perspectives are different. He knows that the efficiency of the new system will break 13%, but Wei doesn’t know it, so it’s normal that the other party does not have a high profile. .
Wei Xingsi is usually more conservative when it comes to submitting articles. He doesn't want to repeatedly modify or switch.
Han Jiaying’s article from NC has been published last week, briefly reporting the progress of the experiment:
J2 and J3 have been synthesized, but the performance has not yet come to test.

Wei Xingsi nodded: "Okay, hurry up and test this week."
Han Jiaying continued: "That's right, and Xu Qiu arranged for me to work on the ITIC-Th system."
Wei Xingsi was not too surprised: "Yes, you can discuss the specific allocation by yourself."
Wu Shengnan was mainly doing synthesis last week, so he did not prepare a 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 was temporarily put on hold..."
"IDIC-4F and IDIC-M have not been synthesized yet, but they should be available tomorrow and the day after tomorrow..."
"In addition, Xu Qiu also asked me to take charge of the work of m-ITIC and the four-in-one work of IT-M, IT-2F, IT-2Cl and IT-4Cl."
Wei Xingsi let out an "um", then looked back at Xu Qiu with a little surprise. ‘It’s very courageous. A total of six systems and four jobs have been synthesized, and three articles have been sent out, leaving only one IDIC. ’
Wei Xingsi put himself in the position of Xu Qiu, thinking that he would not give up so much work to others, and then he only left one article, maybe this is the difference between the two, now I have to admit that Xu Qiu Shanlun The ability to produce scientific research results has actually surpassed myself.
Finally, Karen Mok finished her report:
"Last week I conducted device testing and basic characterization on H22:ITIC: and J1:ITIC:PDI4-B4T, two ternary blend systems, and the results showed that..."
"At the same time, I also produced a number of ideas for the ternary system, including J2: IDIC-4F:-4F..."
Karen Mok listed out more than a dozen ternary systems. After all, the ternary system is just a chance. There is no problem in trying more.
Anyway, there is not much difficulty in the experimental operation. You only need to prepare all the solutions first, and then apply two devices for each solution to test the water. If there is a surprise in efficiency, then conduct an in-depth study. If the performance is mediocre, then just abandon the system or give it another chance.
The group meeting was over, and the few articles submitted before the holiday, except for Duan Yun's rejection, there is no news about the other articles, 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 for an exciton binding energy test. He gave them an IT-4F system as an entry at will. This will also be Tian Qing’s main work afterwards, that is The exciton binding energy, exciton diffusion distance and other properties of the new donor or acceptor materials were found out, and a set of databases was constructed.
In fact, the current structure of the organic photovoltaic field in the group is close to the model of a large group, that is, a clear division of labor and cooperation, Xu Qiu is responsible for overall planning, and everyone below is responsible for a small specific direction, and finally unified and integrated. At first, like Wu Feifei, Chen Wanqing, Tian Qing, and Duan Yun, the four people had four research directions, each fighting each other.
Han Jiaying began to prepare devices and explored the performance of J2 and J3 materials. Chen Wanqing continued to paddle and write papers. Wu Shengnan went to Zhang Jiang to do synthesis. Now the synthesis of non-fullerene receptor materials is mainly entrusted to her.
Xu Qiu is going to perform data processing and fitting of ITIC exciton diffusion distance. Before this, he also needs to confirm the film thickness of the sample.
Previously, the premise of reversing the thickness by the sample absorbance was that the sample thickness at a certain absorbance was known, and the films were all on the scale of a few nanometers, tens of nanometers, and one hundred nanometers. It was 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 for confirming the thickness of micro-nano samples. Other methods include ellipsometer, step meter, atomic force microscope, and so on.
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 spin-coat the sample on a glass sheet, then use a glass knife to cut the substrate from the middle, then break it, and finally use SEM scan and take pictures.
Of course, this method is also limited.
If this method is used to test a 100-nanometer film, the problem is not big, but if it is a few nanometer film, the difficulty is relatively greater, because it basically reaches the resolution limit of SEM, especially the SEM on the first floor of the material. The resolution is even worse for products that are being eliminated in the early days.
Therefore, Xu Qiu deliberately applied two thick "films" of ITIC and IDIC. Among them, IDIC is a precautionary measure. Although it is not available today, it will definitely be available later.
According to the concentration and speed of the spin coating solution, Xu Qiu initially estimated that the film thickness of both should exceed 100 nanometers. Anyway, it is not in the preparation of devices, as long as the film is uniform.
The SEM test was successfully completed.
In the evening, Xu Qiu got the final fitting result. The exciton diffusion distance of ITIC was 14.4 nanometers.
This result was in line with his expectations and was an expected result.
According to literature reports, the exciton diffusion distance of the standard P3HT material is about 10 nanometers. The ITIC system cannot prepare thick film and large-scale devices, so its exciton diffusion distance is equivalent to that of the traditional polymer donor material system, and it is easy to understand. .
On Tuesday, Xu Qiu continued the IDIC system's exciton diffusion distance test, and the final fitting result showed that the IDIC's exciton diffusion distance was 16.8 nanometers.
This is an unexpected result.
The exciton diffusion distances of IDIC and ITIC are 16.8 and 14.4 nanometers, respectively. Although there is a gap between the two, the difference is only about 17%. This gap is not enough to fully explain why the IDIC system can prepare large-scale, thick-film devices. The other ITIC system cannot.
Xu Qiu analyzed two possibilities:
First, the previous inference process may have problems and need to be re-argued; second, the experimental data obtained from 90 data points is not enough, and the error of the fitting results 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 data abnormalities, or "singularities".
If the singularity is not discarded, the final fitting result is likely to deviate greatly from the actual result, but if the singularity is discarded, how to define the singularity is a problem, and the subjective component is very large.
In other words, in the process of data fitting, there is a lot of room for manipulation. Sometimes you can fit what data you really want.
For example, a group of numbers, 10, 15, 20, 25, 30, the average value is 20, if 10 is considered a singularity and discarded, the average value of the remaining four data changes to 22.5.
In linear fitting, this operation has relatively little influence on the result, but now the fitting of exciton diffusion distance is nonlinear. If a few less
singular

singular points
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 suspects that there is an error in the fitting result. If the real result is what he tested it out, he will definitely not "operate".
Because once this kind of thing starts, there is no turning back. You can only continue to weave lies and use one lie to whitewash another.
Anyway, even if the reason why the IDIC system can prepare thick films cannot be analyzed, it is good to report the real situation.
Just say sincerely: "We have discovered a unique experimental phenomenon ~EbookFREE.me~ but we can't explain it yet", and then we can leave this problem to other researchers or solve it by ourselves in the future.
After determining this keynote, Xu Qiu handed over the ITIC and IDIC exciton diffusion distance test experiments to the simulation laboratory for mass repetition.
On Wednesday morning, Xu Qiu got the results of the simulation laboratory 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, the previous fitting results do have certain errors due to insufficient data.
Moreover, with the increase and decrease, the results of the exciton diffusion distance between ITIC and IDIC have been opened by about 48%, which is not small.
Therefore, the previous conclusion can be retained, and it is believed that the improvement of the exciton diffusion distance is one of the main reasons that "device performance is not sensitive to thickness and size".
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