Chapter 172: PCE Eleven?

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Around 1:30 in the afternoon, Chen Wanqing and the others returned to Caiyi 216 one after another.
Xu Qiu felt that it was necessary to talk to them about the matter at noon, especially the senior sister and Wu Feifei, the two of them were also the main members of the glue spreading machine, so he said:
"The heated glue spreader delivered by Teacher Gong arrived at Caiyi this morning. I just took it back from the concierge and put it directly in the spin coating glove box."
"Has it been installed?" Wu Feifei asked.
"It's installed."
"There is no leak in the glove box, right?"
"Although I encountered some minor troubles, it has been resolved. I finally checked the air tightness of the glove box and there was no air leakage."
"What about the original homogenizer?"
"Oh, I put it in a box and put it in the corner of the laboratory." Xu Qiu explained patiently.
"That's good." Wu Feifei finally nodded with satisfaction.
It’s not surprising that Wu Feifei turned into a problem baby. After all, she is the person in charge of the spin-coated glove box. If something goes wrong, she will not escape the sanction of Teacher Wei.
"Is the heating function of the new instrument easy to use?" Chen Wanqing answered. She recently planned to study the effective layer film of the P4T system at different processing temperatures. This instrument is still quite important to her.
"I don't know, I was only responsible for the installation," Xu Qiu pointed to the laboratory and continued: "I gave Han Jiaying the heating function to try."
"Okay, I'll go take a look."
Soon after the school sister left, Feifei Wu suddenly asked: "You said the thermal spin coating method for organic use can be replicated in the perovskite system?"
Xu Qiu said without hesitation: "I think I can at least give it a try. Anyway, now that the instrument has arrived, it is always right to try."
Immediately, he thought for a moment and asked: "Have you seen any related hot spin coating articles?"
Wu Feifei shook her head and said: "At this stage, we have not seen such work. Everyone is mainly working on new perovskite materials. By regulating the molecular structure, there are occasional tasks such as additives and post-processing."
Xu Qiu touched his chin and analyzed:
I guess it’s because perovskite photovoltaics is a field that has just emerged in the past two years. There are too many research directions. Maybe it’s almost time to wait until the general research is almost done, like organic photovoltaics. Under the circumstances, researchers will find a different way and find some subdivided research directions. Of course, it is not ruled out that some people have tried thermal spin coating and then discovered that thermal coating is not a good method for the existing perovskite system."
"I didn't expect your thoughts to be very clear," Wu Feifei's eyes lit up and said with a smile: "It seems that we can discuss more when we are free, and get some suggestions from you."
"I can only give some immature suggestions." Xu Qiu hurriedly waved his hand and said modestly:
"You have published a top issue like EES, you still need to come to me to discuss it."
"My EES is a review article. I can publish most of the luck. The main reason is that the big guys are busy with efficiency. There are not many people who write reviews, so I picked up a leak." Wu Feifei said:
"The gold content of the review is far worse than the specific experimental work. By the way, didn't you vote for an AM before, how is the situation now?"
"It's been almost two months since I submitted the paper, but I haven't received any news yet," Xu Qiu said with a little depression:
"Ms. Wei checked the account backstage last week and said that the article was being submitted for review. He also sent an email to the editor to remind him. He didn't know what the situation is now."
"It is estimated that the speed of reviewing manuscripts is relatively slow," Wu Feifei comforted:
"Good things are too hard. Maybe you can receive the news tomorrow, and the article will be accepted directly."
"I borrow your good words."
...
After a short break, Xu Qiu went to the laboratory.
He originally arranged four experiments for Han Jiaying this week, but she has only completed two so far.
But now she has a new task. On the one hand, she has to explore the optimal experimental conditions based on the heated homogenizer, and on the other hand, she has to prepare Saturday light source samples.
Obviously, she had no time to help him experiment.
There was no way, so I had to play in person.
When walking through the glove box, Xu Qiu saw the school girl operating inside the glove box, and the school girl was watching.
He walked over, stood between the two, and asked casually: "How does the new instrument work?"
"This instrument is really powerful," Han Jiaying said with joy:
"I tried to apply more than a dozen pieces of glass, and the success rate of applying the film so far...what is your guess?"
Looking at her appearance, there is no need to conservatively estimate it. It must have not failed. Xu Qiu calmly said:
"100%."
"Bingo, brother understands me." Han Jiaying said happily: "All succeeded."
"Yes, yes, what about the temperature control of the instrument?" Xu Qiu asked.
"The temperature control is very stable. The temperature deviation during the spin coating process is within..." Han Jiaying thought for a while and said: "Within plus or minus 3 degrees Celsius."
"Not only that, the quality of the film obtained is good, and the center of the film will not appear as a big circle like before." Chen Wanqing also added with a smile.
"That's good." Xu Qiu nodded, these are all expected results.
After understanding the basic situation, he did not rush to leave, and stayed for a while to watch the school girl's experimental operation.
On the heating stirring table on the side, the heating temperature of the solution is 100 degrees Celsius, and the setting temperature of the spin coating instrument on the other side is also 100 degrees Celsius, the rotation speed is set to 3000r.p.m., and the rotation time is 35 seconds.
Start the experiment.
Han Jiaying first clamped a piece of clean glass, and after blowing the surface with a nitrogen gun for about 1 second, placed it in the center of the suction table;
Then unscrew the solution bottle cap on the heating stirring table;
Then press the start button of the homogenizer, and after the platform starts to rotate for about 3 seconds, quickly use a pipette to 20 microliters of solution, and spray the solution onto the high-speed rotating substrate;
After completion, squeeze the pipette tip into a special trash can and discard;
Finally, tighten the cap of the solution bottle.
The whole process went smoothly.
"It deserves to be the apprentice I brought out." Xu Qiu blurted out.
As soon as he finished speaking, he felt a little embarrassed, how could he accidentally express his inner thoughts.
Chen Wanqing did not speak, but stared at him with a smile.
Han Jiaying gave him a white look, and said in cooperation: "Yes, yes, they are all taught by seniors."
However, this disgusting tone...
It seems that it is not suitable to stay here for a long time.
After Xu Qiu gave a few words, Guo broke and ran to the vapor deposition glove box next door.
There are also many experiments he will do today, to supplement the CELIV and TOF data of the four systems.
...
After such a small episode, Han Jiaying stopped the spin-coating experiment based on glass sheets.
She has basically figured out this new instrument.
At present, it seems that it can greatly reduce the operating difficulty of the true thermal spin coating method, almost down to the ordinary spray method.
Of course, whether the new method can replace the original operation method, and the specific effect, still needs to be verified by the device test results, which is also the task Xu Qiu gave her.
Han Jiaying looked at the senior sister next to her, and took the initiative to say: "I'm going to use the new instrument to make a batch of devices. Does the senior sister have a system?"
"Um..." Chen Wanqing thought for a while, and said, "Let's make a few slices. The solution is in my lock box, marked as P37P, P55P and P73P. The date should be around December 5th, and there should be leftovers. some."
The solutions of the three systems of P37P are based on the blending solution of her ternary conjugated copolymer system and PC[70]BM. P37 represents the molar ratio of the two A units in the donor material, and P represents PC[70] BM.
This is a simplified version of the labeling form.
Because the optimal conditions have been figured out, the conditions such as solvent, concentration, and DA ratio are fixed and can be omitted, just indicate the material and date.
After all, the small brown bottle containing the solution has a brown body. It is difficult to distinguish the characters written with a marker. The diameter of the bottle cap that can be written is only about 1 cm, and there is not much space.
Instead of writing a bunch of dense small characters, it is better to be more atmospheric and mark the main content.
The elder sister's lock box was placed on the innermost shelf of the glove box. Han Jiaying tried very hard to reach out in that direction, but still couldn't reach it.
No way, her hands are short, and the depth of the glove box is more than one meter.
Fortunately, this is not the first time she has encountered this situation. She picked up a pair of tweezers about 30 cm long, clamped one end of the lock box, and took it off.
In order to ensure that the solution bottle does not turn over, the whole process is very stable.
Afterwards, she opened the four locks next to the lock box and found three bottles of the target solution from the sister's solution box. After checking, she found that there were more than 200 microliters of solution, and there was no obvious solid residue on the inner wall.
In the organic solution prepared in the laboratory, if the initial solution volume is 1 ml, then 200 microliters is an important threshold.
When the remaining solution volume is less than 200 microliters, the solution is usually discarded unless it is used for some less important experimental characterization.
Because the concentration of the solution at this time will have a very large deviation compared with the initial preparation, the deviation usually exceeds 20%.
Han Jiaying transferred the three bottles of solution to the sample Tito on the heating and stirring table, and then asked: "Is it necessary to do these three systems?"
"Yeah," Chen Wanqing nodded and added: "Actually, it's mostly experimental. My system has used thermal spin coating before, but it didn't work."
"What about the spin-coating conditions?" Han Jiaying asked as she buckled the lock box, picked it up with long tweezers, and put it back in place.
"The conditions are still the same as before, I'll look for it..." After speaking, Chen Wanqing's gaze swam through a row of notes on the edge of the glove box.
These sticky notes are affixed to a position that does not affect the normal use of the glove box, and usually contain experimental conditions, experimental procedures, and experimental memos.
The sticky note is quite convenient to use, just tear it off when you don't need it.
However, when the laboratory was initially established, Tian Qing directly used a black marker to write on the glass of the glove box for the convenience of the experiment.
Later, she was stopped by Chen Wanqing and Wu Feifei, the two glove box leaders. Tian Qing also deeply realized her mistake and erased the writing with acetone.
Later, they all used sticky notes to record information.
A few seconds later, Chen Wanqing pointed to a sticky note and said:
"That's it, the condition is 2500 speed... By the way, how many pieces do you plan to make in total?" Chen Wanqing said.
"I have already made 24 zinc oxide substrates in the morning. Let's use them all today." Han Jiaying said.
"How about giving me six pieces?" Chen Wanqing tentatively asked:
"Three pieces were compared with the optimal conditions before, and three pieces were heat-coated at 100 degrees Celsius."
"No problem." Han Jiaying glanced at the content of the note again, and at the same time remembered the location of the note.
"Then you make the device first, and I will come back after you finish it. Thank you." Chen Wanqing said that she also had an experiment today, but she still gave the glove box to Han Jiaying. After all, the process of making the device is long. The priority is higher.
"Okay." Han Jiaying nodded.
When Chen Wanqing left, she suddenly said: "Brother, what system are you going to do?"
Xu Qiugang installed a device in the sample tray and was about to test CELIV. However, he only listened to the beginning of the conversation between the two seniors, and then focused on experiments.
After hearing the keyword "senior brother", he was stunned for a moment, and quickly reacted, saying, "Let me think about it first."
His system has been proved that the thermal spin coating method is effective, so the initial strategy should be to directly select the best material and fine-tune it.
If the performance of the device can be further improved, it will not be too late to extend it to other systems, and the final result can be updated in the article he submitted to AM.
Xu Qiu quickly made up his mind and said:
"I only need to make one system, P2FBT4T-2OD and PC[70]BM. You should know where the solution is. If possible, you can watch it."
"Let me watch it," Han Jiaying whispered, "Brother believe me so..."
"what did you say?"
"It's nothing, brother, feel free to experiment, and leave it to me here."
...
Throughout the afternoon, Xu Qiu was busy with his experiments, and only occasionally chatted with Han Jiaying, but they had nothing to do with the specific experimental details.
The general direction has been pointed out, and the specific details are left to her to add. The problem should not be big. After all, the scientific research level of the school girl is still reassuring. He feels that his identity is more and more like a mentor.
Around eight o'clock in the evening, Han Jiaying's device vapor deposition was completed.
Although Xu Qiu didn't care much about her specific experiment process, he still cared very much about the results of the experiment, so he got close to her.
In the laboratory, apart from Xu Qiu and the others preparing for the test, Chen Wanqing is also doing experiments.
However, in the spin-coating glove box on the other side, she was studying the new equipment. She did not have much hope for the three systems of thermal spin-coating devices made in the afternoon.
Her attention is entirely focused on the new research work, which is based on the subdivision work of Xu Qiu's P4T material, to investigate the effect of different processing temperatures on the crystallization performance.
The research group usually has more people at night, because the courses for graduate students are rarely arranged at night, and most of the school activities are during the day.
Outside the office, Tian Qing is working hard to write articles. Because she was too procrastinated, Teacher Wei gave her an ultimatum yesterday. This week, her article must be written, corrected, and voted.
Feifei Wu is reading more than a dozen perovskite-related documents that have just been published. She originally planned to do experiments and try out the new equipment, but the glove box was occupied by the organic trio all day today, so she didn’t have it. Fight with them.
Duan Yun is dealing with thermoelectric data. These days, he has been smiling. The experiment seems to be going well, and it seems that an article will be produced soon.
Although it took him nearly half a year to set up the equipment, his scientific research seems to have entered the fast lane after the equipment was set up.
There is some truth in the saying that sharpening a knife does not cut wood by mistake.
Han Jiaying used tweezers to remove the substrate from the sample holder and put it neatly into two petri dishes.
There are a total of 24 substrates, most of the effective layer films are completely coated, and only one or two of them look slightly flawed.
The electrodes on the device are dazzling and shiny.
Commonly used metal electrodes are gold, silver, and aluminum.
The aluminum electrodes that Mr. Wei uses by default in his laboratory are on the one hand because they are cheap, and on the other hand, they are not bad in performance.
This time the electrodes are shiny and silver, definitely not gold, and the appearance of silver and aluminum electrodes is similar, but it is not easy to distinguish.
Xu Qiu judged by intuition that the probability of silver electrodes is higher, and asked: "Is the silver electrodes steamed this time?"
"Yes, I followed the conditions when my brother made the most efficient device." Han Jiaying nodded and said: "Right, which one shall we test first?"
"I don't know what exactly you have done..." Xu Qiu said helplessly.
"Then I will pick one at random." Han Jiaying said.
After speaking, she held the tweezers and dangling over the petri dish, as if looking for a suitable target.
A few seconds later, she picked a piece of substrate, tilted a corner from the side, then clamped it, and said, "Just this one."
"Okay." Xu Qiu had no comments.
He glanced at the side of the back of the substrate, which was marked "XQ, 110, 2.5K".
If you guessed it correctly, it should refer to 110 degrees Celsius thermal spin coating, 2500 revolutions, which seems to be the best condition for his system.
In the past month or so, it has been a school girl helping him to do experiments. It has been a long time since he has made the device himself, and the specific experimental conditions are somewhat unclear.
After connecting the substrate and the test instrument, Han Jiaying clicks the "Test" button of the computer software.
With a beep, the value on the digital display screen of the source meter began to flash.
This is the first device in this batch. Xu Qiu still cares about its performance. He stared at the indication on the source meter.
Although the bright J-V curve of the device and the specific photoelectric parameters can be displayed on the computer after the test is completed, the real-time reading of the source meter can roughly estimate the short-circuit current density of the device.
He noticed that when the voltage value is 0, the current value is 1.65...mA, because the number changes continuously, so he only remembers the first three digits.
Xu Qiu made a mental calculation. The effective area of ​​the battery is 0.09 square centimeters, so the short-circuit current density is roughly 18-19 mA per square centimeter.
This value is not too low in the field of organic photovoltaics. If the open circuit voltage is around 0.9 volts and the fill factor is around 0.60, the photoelectric conversion efficiency of the device is close to 10%.
After a few more seconds, the test is over.
The computer automatically draws the J-V curve and displays various photoelectric performance parameters.
Han Jiaying has been staring at the computer screen. After seeing the data above, she said excitedly:
"It's over 10%, and the efficiency is 10.12%."
"Yes, a good start." Xu Qiu smiled.
He was not as excited as the school girl. On the one hand, he inferred the result in advance; on the other hand, although the efficiency was high, it did not break his previous record.
Chen Wanqing's voice also shocked Chen Wanqing. She turned her head and looked at Xu Qiu and said to Xu Qiu, "It's more than 10%? It's your system, right."
"It's mine. Now it shows that the film coated with the new instrument is no worse than the previous one. At least 10% of the results are repeated." Xu Qiu said.
"Yes, keep going." The senior sister encouraged and turned around to continue her experiment.
"Let's continue." Xu Qiu patted Han Jiaying on the shoulder.
"Hmm~"
Soon, she measured all six data points on the first device, with the highest efficiency value of 10.18% and the lowest value of 10.05%.
"Brother, the fluctuation of the data seems to be much smaller than before." Han Jiaying said.
"I have also noticed this situation, but I don't know if it's a special case." Xu Qiu said: "I will test another slice of 100 degrees Celsius at the same speed. This condition can be done.
"Yes." Han Jiaying put the tested substrate back down, put it back in the original petri dish, and took the substrate labeled "XQ, 100, 2.5K".
After a few minutes, the test is complete.
The highest value this time is 10.46%, and the lowest value is 10.28%.
"It seems that data fluctuations have indeed become smaller, and the absolute value of efficiency is almost the same as my previous highest efficiency value." Xu Qiu said:
"This time it was measured at 90 degrees Celsius at the same speed."
"Okay." The school girl quickly replaced the substrate and tested.
The highest value is 10.38%, and the lowest value is 10.11%.
Han Jiaying thought for a moment and asked:
"The efficiency is reduced. Should I switch to a system of 100 degrees Celsius and measure 3000 speed?"
"can."
"Improved, 10.68%!"
"Is there any higher speed?"
"There are still 3500 rpm." Han Jiaying directly found the corresponding substrate this time and started testing.
Xu Qiu calculated in his mind that so far, his system has already had three temperature conditions and three speed conditions.
He glanced at the substrates in the petri dish, most of which were marked "XQ", and asked curiously: "How many samples have you made for my system?"
"Brother's has 16 films, Chen Wanqing has 6 films, and mine has 2 films." Han Jiaying finished speaking, and quickly added:
"Don't think too much, I just want to use your system as a reference, find the rules, and then transfer it to my system. After all, your efficiency is high."
"All right, I believe you~EbookFREE.me~Xu Qiu said.
That should be each of the four conditions, the speed is from 2000 to 3500r.p.m., the temperature is from 90 to 120 degrees Celsius.
Not long after, Han Jiaying finished the test.
"This film has the highest rate of 10.92%," she was happy at first, and then sighed softly: "Unfortunately, there is no higher speed."
"Next time I have the opportunity to make another batch," Xu Qiu encouraged: "It is very possible to break through 11%."
From the existing results, under the condition of 100 degrees Celsius, the efficiency increases with the increase of the speed, and there is no turning point.
Then continue to increase the speed to 3500r.p.m. and above, there is hope for higher efficiency.
From 10.92% to 11%, only 0.08%, the problem should not be big.
...
After seeing the hope that the efficiency would exceed 11%, Xu Qiu's mind became more active.
The PTB7-TH donor material, which is now the benchmark in the field of organic photovoltaics, is aliased as PCE10.
Because it is the first reported system with an efficiency exceeding 10%.
Later, after five or six years of development, a large number of international researchers have continuously optimized the PTB7-TH system’s device preparation method, the selection of transport layer materials and electrode materials, and published hundreds of related papers to increase its maximum efficiency to 12%.
But so far, apart from the PTB7-TH system, none of the other organic photovoltaic materials reported with an efficiency exceeding 10% has an efficiency exceeding 11%.
Then, if Xu Qiu's P2FBT4T-2OD material can reach an efficiency of 11% when it is first published, he is eligible to name this material PCE11.
Now, only one step away from this goal.