I Have a Research Support System

In the rest of the day, we can make another batch of devices.

However, only 200 microliters of a 23 mg/ml solution was prepared yesterday, which may not be enough.

So, after lunch, Xu Qiu added another 1ml of the solution.

After preparing the solution, he first etched 12 PEN substrates, then spin-coated PEDOT:PSS on the substrates, and sent the substrates into the spin-coating glove box.

At this time, Wu Feifei was using the glove box. Seeing Xu Qiu stuff a petri dish into the teleportation cabin, she asked:

Are you going to spin coat? About how long it will take.

About half an hour. I don't need annealing. I just need to paint it and wipe it off. Xu Qiu said.

Okay, then you can use it first. Wu Feifei left the glove box.

Wait a minute, she stopped when she saw Xu Qiu enter the glove box, planning to spin coat directly:

I just finished coating the perovskite material. Before you make organic devices, you'd better clean the glove box.

Cleaning? Xu Qiu asked suspiciously.

This cleaning is not washing with water, but using nitrogen to clean the atmosphere in the glove box, Wu Feifei explained:

During spin coating, the solvent in the solution evaporates into the glove box.

The solvents we use to make perovskites are mainly DMF and DMSO, which are polar solvents, while the chloroform and chlorobenzene used in making organic devices are relatively less polar solvents.

These two types of solvents can be said to be antisolvents to each other, that is, perovskite is almost insoluble in chloroform and chlorobenzene, and organic materials are almost insoluble in DMF and DMSO.

Therefore, if there is a large amount of polar solvent vapor in the glove box, it will have an unpredictable effect on the performance of your organic device, and this effect is usually detrimental.

In short, if you want to ensure good repeatability of the devices you make, it is best to clean the glove box every time before spin-coating the effective layer, three to five minutes is enough.

Did Chen Wanqing teach you how to clean it?

No, she probably forgot. Xu Qiu recalled it carefully and said.

Let me teach you. Wu Feifei said, You know how to use the pressure reducing valve.

Yes. Xu Qiu said.

First, adjust the pressure reducing valve of the nitrogen cylinder to the position of 3 bars, usually 5 bars when we use it normally.

Xu Qiu adjusted the pressure reducing valve.

Next, open the touch panel next to the glove box, turn off the circulation system, press the cleaning button, then set the time to 3 minutes, and then click start, and that's it.

Wu Feifei explained while operating.

After Wu Feifei pressed the start button, there was a bang sound in the glove box, as if a certain valve had been opened.

Then, there was a hissing deflation sound, and the two rubber gloves slowly inflated as the pressure in the box increased.

Will this cause problems due to excessive pressure, such as opening the safety valve on the top of the box? Xu Qiu asked.

No, this is a pre-set program. The nitrogen bottle will continue to supply nitrogen to the glove box. After the pressure in the glove box reaches a certain threshold, it will automatically perform a deflation operation to exhaust the gas in the box to the outside. Wu Fifi said.

Exhaust gas is discharged directly, it will cause pollution. Xu Qiu asked.

The amount of exhaust gas we produce is very small, so it is not realistic to build an industrial-grade exhaust gas treatment system, and the glove box is equipped with a filtration device and a condensation device, which can leave most of the solvent.

If human beings want to live better, some price must be paid, just like people know that burning coal and gasoline will cause excessive carbon dioxide emissions and trigger the greenhouse effect, but they will still use it when necessary.

After the cleaning is finished, adjust the pressure reducing valve of the nitrogen cylinder back to 5 bars, turn on the circulation system, and the experiment can be carried out normally. Wu Feifei said.

…………

After cleaning, Xu Qiu continued to spin coat the effective layer.

This time, he had 12 substrates.

So he designed 6 sets of speeds, namely 1800, 2000, 2200, 2500, 2700, 3000r.p.m., each with 2 pieces of speed.

The solution used is 23 mg/mL, PTB7-TH:PC[70]BM solution with acceptor mass ratio 1:1.3, 0.7% volume fraction DIO+chlorobenzene solvent.

Next, vapor deposition, testing.

Xu Qiu first picked the 2500-speed device that he thought might be the most efficient, and started testing.

The first piece, up to 7.89%.

The second piece, up to 8.12%.

He quickly tested the remaining ten pieces, and there was no battery device with higher efficiency.

After copying the data, Xu Qiu approached Chen Wanqing and said:

Sister, my efficiency is 8%.

It went so smoothly, then you can go to Teacher Wei to report the result. Chen Wanqing thought for a while and said, He should tell you to write the article first, and I will go there with you.

OK.

…………

The two came to the 218 office.

Sitting on the swivel chair in front of the desk, Wei Xingsi said:

Tell me, what's the matter.

8% efficiency, a flexible substrate device made by Xu Qiu. Chen Wanqing said.

Okay! Wei Xingsi patted the table, stood up, and said while pacing the room:

Xu Qiu, with this efficiency, the article can be written, written in Chinese first, which can be used as a project conclusion report, and then translated into English.

You start writing from the main text, write out the description of each symbol, and make up for any missing symbols as soon as possible, and get out the whole framework first.

If you have any signs that you can't test, let Chen Wanqing teach you, Chen Wanqing?

Okay, okay, I know. Chen Wanqing didn't react at first.

By the way, have you tested EQE? Wei Xingsi said.

Not yet. Xu Qiu shook his head.

Then test the EQE first. If the device is left for a long time, the test may not be accurate. Wei Xing thought for a while, and then said:

By the way, Chen Wanqing, please bring Xu Qiu with you for the light source test in a few days.

Yeah. Chen Wanqing nodded.

Okay, you guys go to work.

Wei Xingsi opened the refrigerator and found that there was no honey grapefruit tea, so he took two bottles of Evian mineral water and handed them to the two.

…………

After returning home, Xu Qiu tested the EQE curve of the best device and yesterday's P3HT device.

Then, he went to his desk, turned on the computer, and prepared to draw the EQE and J-V curves.

It turned out that he did not have the origin software, so he asked Chen Wanqing for advice:

Senior sister, I haven't given the origin template that I agreed to before. Also, where can I download the software?

The school has free genuine resources, which can be downloaded directly from the campus network, in the genuine software application.

Chen Wanqing copied the template, handed the USB flash drive to Xu Qiu, and said, Do you know how to use the software?

No. Xu Qiu shook his head.

Then let me teach you some basic functions. Origin's functions are very powerful, but we don't need most of them. Chen Wanqing said:

Copy the data from the EXCEL or TXT text directly into the data table of the origin software, and the top of the data table will mark whether it is the X-axis or the Y-axis.

Then select two columns of data, click plot, you can generate a picture, and then apply the template, change the details, such as the legend name, etc., and you are done.

If you want to use multiple J-V curves for comparison in one graph, you can insert a Y-axis on the data side so that they share the same X-axis, then select them together, and then plot.

Xu Qiu tried to do it by himself, and made the two pictures well.