Chapter 319: Wei Xingsi: It is estimated that in a few years, I will follow him

Xu Qiu bound several documents in his hand, and glanced at the content roughly. There is no noteworthy work in the field of organic photovoltaics.
They may all be holding big moves, like Xu Zhenghong's derivatives based on the IDTBR system, it is conservatively estimated that there are two or three AM-level articles on the road.
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Putting down the literature, Xu Qiu got up to report and summarized the PPT of the harvest at the conference yesterday.
Wei Xingsi had requested the PPT of the conference speakers from Gong Yuanjiang, but Xu Qiu hadn't had time to sort out the corresponding pictures and put them in text versions.
First, the two tests mentioned by Bazan:
The exciton binding energy is the energy required to split the bound electron/hole pairs (excitons) into free electrons/holes. The average diffusion distance of excitons, that is, the average distance that the bound electron/hole pairs (excitons) move before recombination emits light/heats.
These two tests appeared more in the early years, aiming at the donor materials in the traditional fullerene system, but now they are relatively rare.
The main reason is that these polymer donor materials are essentially similar to the structure of D-A conjugated copolymers, so the two parameters tested on them are not much different, and the two experiments are very troublesome.
For various reasons, later researchers gradually became too lazy to carry out these two characterizations, and could not come to any new conclusions to say, and it was troublesome to test.
The general conclusion for the fullerene system is:
On the one hand, the exciton binding energy of donor materials is generally high, resulting in relatively low open circuit voltage of organic solar cell devices. Materials with the same band gap may be 0.3 lower than the open circuit voltage of inorganic silicon solar cells or perovskite photovoltaic devices. Volt or so.
What is this concept? Take dry batteries as an example. Inorganic silicon or perovskite is like normal No. 5 and No. 7 batteries. The voltage is about 1.5 volts, while the voltage of organic photovoltaics is only 1.2 volts.
Under other conditions, the organic photovoltaic device is born with a photoelectric conversion efficiency of about 20% reduced to DEBUFF.
On the other hand, the average diffusion distance of excitons is also very short, about 10 nanometers.
This means that most excitons can only diffuse a distance of 10 nanometers after they are produced. If they are farther away, the excitons produced by absorbing sunlight will recombine and become light energy or heat energy lost again.
This is why organic solar cells cannot use planar heterojunctions for effective layers like silicon-based and perovskite solar cells, but bulk heterojunctions must be used.
Because only by forming a bi-continuous three-phase blending structure and ensuring that there is a dimension of 10 nanometers in each phase zone, can it be ensured that the generated excitons will not be recombined in a large amount before being split and collected by the electrode. .
Once the size of the phase region is too large, such as more than 20 nanometers, or more than 100 nanometers like a planar heterojunction, the excitons generated by the effective layer located in the central part after light absorption have not had time to diffuse to the interface. Recombination and consumption, causing the central area of ​​the effective layer to become a dead zone, will not contribute to the improvement of the device efficiency, and thus stack one? The% efficiency is reduced to DEBUFF.
Similarly, the short average diffusion distance of excitons also prevents organic solar cell devices from making thick films several hundred nanometers thick, and can only prepare thin films with an effective layer thickness of about 100 nanometers.
A 100-nanometer film may only absorb about 80% of the sunlight, and the remaining 20% ​​will be lost directly through transmission. If the film can be made thicker, such as 300, 500, 800 nanometers, the light absorption may reach Above 99%, the transmission loss can be basically ignored.
The effective layer of the thin film of about 100 nanometers again allows the organic photovoltaic device to be superimposed with an efficiency of about 20% and reduced to DEBUFF.
Several DEBUFFs are superimposed together, and if a bit is lost in the transmission layer, interface, light reflection, etc., the final device efficiency will be low...
This is why, according to the SQ limit, the theoretical limit of the photoelectric conversion efficiency of single-junction solar cells is about 30%, while in the field of organic photovoltaics, it is actually only about 12%, which is really too much of a hindrance...
However, these theories are based on the traditional fullerene system, that is, only the donor material absorbs sunlight to produce excitons.
For the non-fullerene system that is slowly emerging now, the acceptor material will also absorb sunlight. Xu Qiu intends to regain these Swire testing methods and test the water with the ITIC material he developed to see if he can get it. Some new theories came out.
If you can get any subversive conclusions, coupled with high device efficiency as a proof, you have the opportunity to write a big article.
Next, Xu Qiu continued to introduce the gains he got from Gong Yuanjiang, Lu Changjun, Zang Chaojun and others, which was relatively trivial. It was the inspiration he caught when his thoughts collided and had a brainstorm when listening to the report.
These inspirations are relatively advanced, and they are all ideas that have not been tried in the current group, including: "Making Wu Shengnan's FNIC system to prepare translucent devices", "Multiple systems with complementary light absorption to prepare laminated multi-junction solar cells", "Organic photovoltaics" "And perovskite photovoltaics are prepared in the form of non-multijunction devices", "three-element devices based on two light-absorbing complementary non-fullerene receptors" and so on.
Finally, Xu Qiu introduced another more systematic work from Xu Zhenghong's research group, that is, how their group continuously optimizes the ADA non-fullerene receptor molecule based on Rao Danning A unit structure, and obtains the current The IDTBR structure.
Xu Qiu also helped Xu Zhenghong look forward, and then he could carry out "Introduction of fluorine atoms in the BT unit", "Replace the two thiophenes at the end of IDT with benzene rings", "Introduce cyano groups into the end groups of Rao Danning" Series optimization.
Of course, he just said casually, and didn't mean to do it himself. Xu Qiu can do a dozen systems now, which is enough for him to digest for a while.
While Xu Qiu was reporting, Wei Xingsi had been listening carefully. Before on the train, he simply glanced at Xu Qiu's PPT without taking a closer look.
As a result, Wei Xingsi became more and more frightened as he listened. Although there are only a few pages of PPT and a dozen lines of text, he has gathered scientific research ideas in nearly ten research directions. According to his understanding of these scientific research ideas, more than half of them Everyone has the opportunity to publish articles, and many ideas have the potential to publish articles in one area.
Is this the harvest of taking Xu Qiu out for a meeting for a day? It is so terrifying...
Wei Xingsi couldn't help but recall the changes in the past year after Xu Qiu entered the research group:
In the beginning, Xu Qiu took the initiative to send an email saying that he would join the research group for an internship. The idea at the time was that a free labor force was finally coming.
After meeting with Xu Qiu in person, I learned that Xu Qiu has a 3.5 grade point and his English score is also very good.
Preliminary judgment is that if you train well, you should be able to contribute three or four articles in the second district. With good luck, you may be able to produce one or two articles in the first district.
Then, I let Chen Wanqing take Xu Qiu to familiarize himself with various experiments, and let him take over an unfinished school project, which seemed to be about flexible substrates.
I didn't pay much attention to this, after all, I was an undergraduate.
It didn't take long for him to get the project closing report, and he actually posted an article. The article was not bad. If I remember correctly, it should be a "Big Mole".
Next, Xu Qiu learned the polymerization reaction, and independently developed PCE11 by himself, and posted an AM directly in front of the Yanhu research team of the University of Hong Kong.
At that time, he felt that it was pure luck. Well, he picked up a leak. Although this is rare in the scientific research field, it is also true.
Later, the face-slapped, 3D-PDI system, Xu Qiu published an NC again, breaking the world record in the PDI field, and did what I wanted to do but did not do. UU reading www.uukanshu.com
Although this world record was quickly surpassed by Han Jiaying, Xu Qiu would definitely not be able to do this if he had only luck.
He is really capable, and his scientific research level should be about the same as when I was young...probably?
At this time, I had a plan to let him be the small boss of the research group.
Recently, he has crossed the field again, came to the ADA system, and developed an ITIC system with an efficiency exceeding 10%, continuing to create miracles.
I also formally promoted him to the position of the small boss of the research team, and plan to arrange for him to go abroad for two years after graduation, and then specially hire him to come back to pick up my class.
Now, seeing his scientific research ideas emerge in endlessly, it seems that there is no end.
According to this trend, let him take a hammer class. It is estimated that in a few years, I will follow him...
PS: I asked for a recommendation ticket on Monday. The two chapters were simply sent directly together, and the third one was at 16:00 in the afternoon.