I Have a Research Support System

The sample that Xu Qiu and the optoelectronic company in Shencheng had asked for had already been sent to the material concierge.

He hurriedly took it back. There were a total of seven polymer donor materials, ranging from 10 mg to 20 mg each, packaged in small glass bottles. He didn't deliberately shy away from others, and simply explained the way down.

The materials were blue, purple, or black fibrous. After Xu Qiu inspected them, he was very satisfied. He copied them into the simulation laboratory and put them in the spin-coating glove box for storage.

After reporting yesterday, he chose courses on the course selection website. There is only one "Graduation Project" this semester, which is equivalent to no classes. Dr. Chen Wanqing is a second year student and has completed all courses. on Monday.

So, after lunch, the organic trio took the school bus to Zhang Jiang's laboratory.

Chen Wanqing completed the aldylation of unit D last week and successfully purified it, and this week plans to re-synthesize unit A which failed last week.

Xu Qiu and Han Jiaying plan to continue the third step of the PDI system to synthesize dimer PDI.

There are two types of dimers of PDI, one is bridging type and the other is torsion type.

Bridging type synthesis, two molecules of monobrominated PDI react with a molecule of D unit substituted by trimethyltin to form a structure of PDI-D-PDI, and the D unit can be thiophene, dithiophene, vinyl, etc. The unit of the yoke structure, the reaction principle is the Stille reaction, which is similar to the previous synthesis of the polymer donor molecule, but because the PDI is substituted by monobromine, the reaction will stay in the dimer and cannot continue to react to form a polymer.

The synthesis of torsional type is a new reaction. Two molecules of monobrominated PDI undergo a coupling reaction under the action of zinc powder and zero-valent palladium catalyst to obtain the structure of PDI-PDI. DMF is usually used as a solvent.

Although it is considered a new reaction, the difficulty of the two reactions is not great, and it is an entry-level experiment.

In the office, only Xu Qiu and Han Jiaying were preparing for the experiment. Chen Wanqing was just repeating last week's experiment, so there was no need for preparation.

"Brother, how do we divide the work?" Han Jiaying asked while sitting at the computer.

"Each person voted for two responses, one for bridging and one for twisting," Xu Qiu said casually, "just follow the order we synthesized earlier, I'll make No. 1 and No. 2, and you will do No. 3 and No. 4." , No. 1 and No. 3 bridging type, No. 2 and No. 4 twisting type, each injecting 100 mg to test the water."

"No problem." Han Jiaying immediately began to operate the laptop in her hand, calculating the dosage of each reactant.

Before, they drew the reaction steps in the CHEMDRAW software, directly selected the molecular structure of the raw material, and the software could calculate its relative molecular mass.

Input the relative molecular weights of several raw materials and catalysts into the preset "feeding mass calculation" EXCEL, and then input the feeding equivalents of several reagents, and finally determine the initial mass of a certain raw material to automatically calculate the weight of each reagent. Feeding amount.

A few minutes later, Han Jiaying picked up four sticky notes, handed two of them to Xu Qiu, and asked, "Brother, are there any precautions for the next experiment?" She has already developed the habit of asking Xu Qiu before the experiment. got used to.

Xu Qiu thought for a while and said, "On the one hand, we must ensure anhydrous and oxygen-free conditions. You should understand that the catalyst uses zero-valent palladium. On the other hand, we must ensure the purity of the product and order it again before the reaction. Board to confirm."

Han Jiaying nodded, and said deeply, "That makes sense. Senior sister Chen Wanqing was a lesson learned last week. Seven or eight sample points are like candied haws."

With sticky notes, the two entered the laboratory and stuck them on the glass of the fume hood.

Speaking of which, the glass of the fume hood was filled with marks by Duan Yun before Xu Qiu entered the research group. Later, at the unanimous request of Wu Feifei and Chen Wanqing, he wiped it clean with solvents such as ethanol and acetone.

Now Duan Yun hardly comes to Zhangjiang to do experiments. His materials, including N2200, PVDF and several kinds of metal nanowires, are purchased from commercial channels, and then directly prepared in the glove box of Handan, and then used He built his own test equipment for testing.

As for the perovskite quantum dot project that Tian Qingxin is in charge of, it is possible to come to Zhangjiang for synthesis later.

...

Start experimenting.

The solvent was distilled again. This time, the four reactions used DMF as the solvent. In fact, toluene was used as before, which is theoretically possible, but it was written in the literature that DMF was used, so they did not change it.

Prepare a reaction bottle, add a magnetic stirrer, and prepare a nitrogen balloon.

Spot the plate to confirm the purity of the drug, weigh the drug, add the solvent, connect the condensing device, nitrogen balloon, and pump three times.

Add the catalyst, pump three times and row three times, heat up rapidly, and protect the reaction bottle with aluminum foil on the outside.

Done, the orange-red solution is like a pot of tomato soup.

The other reaction steps were similar, and Xu Qiu quickly got it done again.

Then, he was surprised to find that Han Jiaying's reaction speed was not much slower than his, only less than a minute behind him.

It's not surprising when you think about it, the senior sister's experiments are of the steady type, so they are relatively slow, and the junior sister's experiments are relatively reckless, a bit like him.

Han Jiaying cleaned up the experimental garbage in the ventilator, and asked casually, "Are we going back to Handan this week to make devices?"

Xu Qiu thought for a while and said, "After the product is purified this time, let's go back and make a few batches of devices."

This is mainly to explain to Xuemei and Teacher Wei that they don't have a simulation experiment system like him, and can directly get the efficiency data. Secondly, Chen Wanqing will also use the liquid chromatograph in the next few days. If they go to Handan, it just happens It can be used in staggered peaks.

"Brother, how efficient do you think it is?"

"I guess 5%-6%. After all, it is almost a complete repetition of the existing system. It can't be higher than the value in the literature." Before the simple PDI molecule could reach 3.5%, and now the modified PDI dimer It is not difficult to achieve more than 5% in theory, unless the synthesis reaction fails.

"It's a pity that this result cannot be used to publish articles."

"That can't be helped. Dimers have been studied for many years, and the molecular structure is limited. Basically, all conceivable structures have been published." Xu Qiu changed the subject: "However, the operating space of 3D-PDI is much larger. Now, the core in the middle can be adjusted at will, and there are many possibilities."

"Actually, I have been thinking about 3D-PDI during this time, and I have some experimental ideas."

"Oh, let's hear it." Xu Qiu's eyes lit up, and he became interested immediately.

"In common organic photovoltaic materials, the application of thiophene ring, which is also an aromatic ring, is obviously more than that of benzene ring. However, in the first 3D-PDI work, they used triphenylamine and did not introduce thiophene." Han Jiaying paused, continued:

"I think it may be possible to improve based on their system, such as connecting three or even four thiophenes to the benzene ring, and then connecting with PDI molecules to form a 3D-PDI structure."

"Brother, what do you think?" After speaking, Han Jiaying stared at Xu Qiu expectantly.

"This idea is good, and it is feasible." Xu Qiu naturally praised her without hesitation. The junior girl was very happy when she heard it, and her eyes narrowed into crescents.

Most of the time before, it was he who came up with experimental ideas and asked the school girl to implement them, but now she has come up with her own experimental ideas, and the analysis is still reasonable.

This made him feel that his son had finally grown up.

In fact, Xu Qiu was not idle during this time, he took the time to list several possible molecular structures.

Then cooperate with the DFT simulation in the simulation laboratory to eliminate some structures with unreasonable steric hindrance, and get more than a dozen feasible solutions, and the idea of ​​the school girl is one of his alternatives.

...

After that, Xu Qiu and Han Jiaying purified the four products.

Because the raw materials are very pure, and there are almost no side reactions in this step, only one main product is obtained, and the difficulty of purification is not high.

The yield is roughly between 50-70%, and there are only a few tens of milligrams of the product, but it is enough for the time being.

Last week, the characterization data of the samples sent by the school girls came back one after another, and the results were almost the same as those obtained by Xu Qiu in the simulation laboratory II. After receiving the news, Han Jiaying and Chen Wanqing were overjoyed.

The school girl was very happy because the characterization results verified her previous conjecture was correct, and her and Xu Qiutou's reactions were all based on her "inference".

The senior sister is because it has been verified that the D unit is substituted with a dialdehyde group, so the post-position reaction can be carried out with peace of mind.

In addition, Xu Qiu and the others also obtained the first batch of device data based on the synthesized PDI molecule, with the highest efficiency of 5.21%. The system is PCE10:PBI-5, and the device is of course made by Han Jiaying.

PBI is the name of the PDI dimer, followed by a number representing the number of carbon atoms in its side chain, or the name of the bridge unit, such as PBI-5, PBI-2-T and the like.

Xu Qiu used the simulation laboratory II, which took 12 hours and 1200 points, based on the four PDI dimer receptors, to initially traverse the existing donor library, and the highest efficiency value was 5.86%.

Then, two preliminary experimental conclusions were obtained:

First, the optoelectronic performance of the bridged PDI dimer is worse than that of the twisted type. Of course, this is only a preliminary conclusion, because there are many variables, and it may also be related to the choice of the intermediate bridge unit.

Second, after the dimerization of PDI molecules, the number of side chain carbon atoms is required to be more than that of simple PDI molecules. Xu Qiu speculates that it is because the scale of a single molecule becomes larger, so more side chains are needed to ensure the original solubility. .

In general, the foundation of the PDI system has been laid.

As for the nominal boss of the organic trio, Chen Wanqing stayed in Zhang Jiang's laboratory, and even went to work overtime on Saturdays.

After two weeks, the hard work finally paid off, and she got the first batch of A-D-A small molecules synthesized by her, which she named C1.

Although both Xu Qiu and Han Jiaying complained about the name, the senior sister didn't intend to change it, it seemed that she was planning to let herself go.

Then, Xu Qiu secretly used the simulation laboratory II to help her experiment on Sunday - based on the current donor library, it took 5 hours, and the highest efficiency obtained from the preliminary traversal was only 0.67%.

emmm...

I don't know how the senior sister will feel when she gets this result.