I Have a Research Support System

After the first draft of the graduation project was completed, Xu Qiu was planning to further refine it, when Qiu Heming came over, this time he came alone, and did not lead his younger brother like last time.

Wei Xingsi entertained Qiu Heming with tea at 218, and then summoned Xu Qiu, Wu Shengnan and Tian Qing.

After the three of them entered, Teacher Wei asked, "Are the samples ready?"

"Ready," Wu Shengnan shook the petri dish in his hand slightly, and replied proactively: "Including P3HT standard samples, and two samples of organic conjugated polymer materials synthesized by myself."

"Okay," Wei Xingsi nodded, and continued: "Tell me about the results of the P3HT test. I have data from the literature here. Let's see if it can be matched."

As an old-fashioned conjugated polymer material, the performance of P3HT in all aspects has been excavated very deeply. As long as the experimental characterization is slightly involved, it will be tested by various researchers to see if it is possible to water an article , the data of fluorescence quantum yield is naturally also available.

"It's definitely not a problem. Each of our products has been tested before leaving the factory." Qiu Heming said confidently. After speaking, he opened a small cardboard box that he carried with him, removed several layers of bubble wrap shockproof packaging inside, and took out the integrating sphere inside.

Xu Qiu took a closer look. The integrating sphere Qiu Heming brought was the same as the picture he posted earlier. The whole body had the texture of white plastic, and it might have been directly fired as a whole with a mould.

The integrating sphere is designed to be attached to the sample compartment, but before use, it is necessary to remove the sample card slot in the original sample compartment with a hexagonal screwdriver, and then install the special card slot for the integrating sphere.

After the equipment debugging, Qiu Heming instructed Wu Shengnan to start the test, while Xu Qiu and Tian Qing watched from the side.

Soon, the first standard sample test of P3HT was completed.

Qiu Heming exported the data, then copied an EXCEL file named "PLQY (fluorescent quantum efficiency)" from the USB flash drive he carried to the computer desktop, and then opened the file.

This is a read-only file with several spaces for parameters.

While processing the data, Qiu Heming introduced: "We input the data obtained by TRPL manually, and then we can directly fit and calculate the fluorescence quantum efficiency of the sample. For example, for this P3HT sample, the value of PLQY is..." Qiu Heming was stunned After a while, he wondered: "Only a few percent, is this a photoluminescent material?"

"Oh, P3HT is an organic conjugated polymer with photoluminescence phenomenon, but it is not used in the field of photoluminescence. Now we mainly use it as a standard sample for detection, and the value is right. At present The gap with the literature is not that big, you continue to test." Wei Xingsi's voice came from outside, and the TRPL instrument was placed in the utility room of his office, so they could hear each other talking.

Xu Qiu can understand the reason why the fluorescence quantum yield of P3HT is relatively low, because it is a photovoltaic material, which is mainly used to convert light energy into electrical energy.

And if the fluorescent quantum yield of a material is high, it means that all the absorbed sunlight energy is converted into fluorescent light and emitted, and the energy is conserved. If most of it is converted into light energy, then the part converted into electrical energy will naturally become If there is less, the photoelectric conversion efficiency is probably not good enough.

Afterwards, Wu Shengnan operated and tested several other samples of hers, and the values ​​of PLQY ranged from more than 10% to 30%.

These numbers are neither high nor low.

After all, for some materials such as phosphors, it is possible for the fluorescence quantum efficiency to exceed 90%. Some materials even obtain a fluorescence quantum efficiency of more than 100% due to chain excitation, that is, absorb one photon and generate more than one photon, and the extra photon is similar to the chain reaction of nuclear fission. Tertiary fluorescent photons produced by excitation of secondary fluorescent photons.

However, her materials are mainly electroluminescent color-changing materials, and the data of PLQY is not important. Wu Shengnan mainly studies the fluorescent color-changing phenomenon of her materials under different voltages, and the response time of the color-changing.

The main thing that needs to be characterized by PLQY is the perovskite quantum dot material, but it has not been successfully synthesized yet.

Objectively speaking, the preparation of quantum dot materials is really difficult, because quantum dots are zero-dimensional point-like nanoclusters, and the scales in three dimensions are at least less than 100 nanometers.

Quantum dot pairs of different materials have different scales. Some scales are less than 100 nanometers, while others need to be less than 20 nanometers or 10 nanometers. There is no uniform standard for the scale of materials, mainly to see whether there are quantum effects in materials. If there is a quantum effect, it is a quantum dot; if there is no quantum effect, it is an ordinary atom/molecular cluster.

It is easy to imagine that this kind of quantum dot material with a scale of several nanometers or tens of nanometers is very unstable due to its high specific surface area and high activity on the surface of the material, which is prone to chemical reactions or agglomeration.

The surface is usually connected with a ligand or a passivation layer, like the oleic acid surfactant Wu Shengnan used before, in order to allow the perovskite quantum dot material to maintain the state of quantum dots without agglomeration. Unfortunately, she used the solution method and heat Injection methods all failed.

Wu Shengnan decided that the hot injection method was more promising and was going to continue to try.

After the sample testing, Tian Qing, Wu Shengnan and Qiu Heming discussed some TRPL testing issues. Xu Qiu didn't go to join in the fun, after all, he had already copied Qiu Heming's skills.

"Dr. Qiu, stay for a light meal?" Wei Xingsi said politely, "I've troubled you a lot during this time, and I've come here twice in person."

"It should be, I'd better go home and eat." Qiu Heming waved his hand and declined, he also settled in the magic city, but he was not an aborigine, but took root in the "magic drift" for nearly twenty years.

After five o'clock, Chen Wanqing returned to the Handan campus. After returning to 216, she took out a garbage bag from her schoolbag, which contained the materials and intermediate products she had synthesized, and then walked towards the laboratory.

Xu Qiugai had a headache after changing her graduation project, so she followed her into the laboratory and took the initiative to talk to her: "Senior sister brought back so many bottles, what a bumper harvest."

"It's okay," Chen Wanqing replied while operating in the glove box: "This time, I synthesized two receptor materials, IDT-BT-ICIN and IDT-T-ICIN. Originally, I planned to synthesize only one Yes, the experiment failed once in the middle, in order to prevent nothing to report at the group meeting, another thiophene (T) unit was added on the basis of the original BT unit.”

"That's it." Xu Qiu nodded, copied her two materials into the simulation laboratory II, arranged for simulation experimenters to optimize performance, and then asked casually, "Are you planning to continue the synthesis next week?"

"Stop for a while, let's make devices." Chen Wanqing chuckled lightly, and laughed at herself: "Now I feel like I'm about to be marinated by organic solvents, so I need to slow down and let my body metabolize the organic solvents absorbed during this period. go out."

"It sounds quite reasonable." Xu Qiu still agrees with the senior sister's point of view.

According to his understanding, the human body's immune system is very strong, and poisonous and harmful substances ingested in small amounts can be gradually eliminated through normal metabolic processes.

Of course, like a firewall, the immune system has limits and loopholes.

The so-called "limit" means that for toxic substances exceeding a certain dose, due to the processing speed of the immune system, it may cause irreversible damage to human organs and tissues before they are completely eliminated.

The "loophole" is that heavy metals have an enrichment effect, and the combination of fluorine elements is stable. Once they are taken into the body, there will be more and more, and it is difficult to eliminate them. In fact, it is not that the immune system cannot handle them, but relatively speaking, the processing speed is relatively slow. In theory, if the intake is stopped, the content of these elements in the body will definitely decrease until one day tends to a safe level. range, but maybe this time span exceeds the normal human lifespan, such as hundreds or thousands of years, which is a bit similar to "as long as you die, your disease will be cured".

The next day, early on Saturday morning, Xu Qiu got the device results of the senior sister's system.

The IDT-BT-ICIN system, whether it matches with narrow bandgap polymer donors such as PCE10 and PCE11, or matches with wide bandgap polymer donors such as H11, H12, and H13 developed by Xuemei, the device performance is not good. , the highest efficiency is only 2.8%.

On the contrary, the highest efficiency of the IDT-T-ICIN system reached 6.1%, the optimal donor material was H13, and the efficiency value was comparable to that of the previous IDT-ICIN system.

Xu Qiu thought for a while and found a further optimization direction, which is to modify the side chain of the newly introduced thiophene unit, mainly because the newly introduced thiophene unit increases the conjugated length of the molecule, but there is no new side chain, and the solubility is slightly Some pressure.

One method is to directly add alkyl side chains, such as dendritic short side chains such as 2-ethylhexyl, which only increase the solubility without greatly affecting the light absorption performance and energy level structure of acceptor molecules. .

Another method is to introduce heteroatoms, such as side chains with oxygen and sulfur heteroatoms, while introducing side chains, which will have unpredictable effects on the performance of the molecule, good or bad, but anyway , can be used as a potential optimization direction.

As for the system of BT, the efficiency base is too low, and Xu Qiu is not sure whether it can be saved, so he is not interested in dealing with it for the time being.

After the analysis, Xu Qiu felt lucky for her senior sister. She failed the experiment halfway, which was a blessing in disguise. She synthesized additional IDT-T-ICIN materials. , if only IDT-BT-ICIN is synthesized, most of the group meeting will cry again.

After all, there is no difference between the efficiency of more than two o'clock now and the efficiency of less than 1% at the beginning.

PS: When counting the number of words in chapters at the starting point, the combination of English letters and special symbols counts as one word, that is, names like "IDT-BT-ICIN" seem to be very long, but the number of words is actually 1. I suddenly thought of this, so let me explain that it is not because of the number of words that the name is so long, but actually when doing scientific research, the naming of materials is like this.