I Have a Research Support System

Xu Qiu opened the system panel.

【Scientific Research Auxiliary System】

Privilege Level: 3

Points: 9978

Tasks in progress: 2

Proficiency:

【Experimental operation class】

Preparation method:

Clean the substrate (fourth stage 45%/fourth stage 80%)

Solution Preparation I (Fourth Stage 40%/Fourth Stage 50%)

Solution Preparation II (Fourth Stage 0%/Fourth Stage 80%)

Spin coating I (fourth stage 40%/fourth stage 50%)

Spin coating II (3rd stage 50%/4th stage 80%)

Evaporation (fourth order 35%/fifth order 0%)

Characterization methods:

Photoelectric performance I (fourth order 40%/fourth order 80%)

Photoelectric performance II (third order 50%/fifth order 0%)

Optical properties (fourth order 5%/fifth order 0%)

Charge transport performance (third order 30%/fourth order 40%)

【Instrument Equipment Tools】

...

【Special class】

Literature reading (3rd stage 1%/4th stage 50%)

Weekly Task II: Experiment for more than 15 hours, and the duration of the simulation experiment will also be included in the task. The current progress (0.5/15 hours), task completion rewards 500 points.

Advanced task: Publish an SCI paper as the first author. Task reward: 2000 points, permission level +1.

##

Xu Qiu discovered that some of his skills were divided into two types, I and II.

Among them, class I is for copying Chen Wanqing's skills on organic photovoltaics, and class II is for copying Wu Feifei's skills about perovskite materials.

The upper limit of proficiency of other common skills has also been raised. It seems that Wu Feifei's scientific research ability is indeed higher than that of her senior sister.

The system points have also accumulated close to 10,000 without knowing it, which should be of great use in the next experiment.

After reading the panel, Xu Qiu turned on the auxiliary system to check the video of the "Spin Coating II" skill just copied.

From the system image, the operation of anti-solvent spin coating is not difficult.

First, drop the prepared perovskite solution evenly on the substrate, and then start the homogenizer.

After about 4 seconds, use a pipette gun to quickly drop toluene onto the surface of the high-speed rotating substrate, and finally a flat and smooth film can be obtained.

Wu Feifei said before that she would meditate in her heart for 5 seconds before adding the anti-solvent. It seems that she meditated relatively quickly, and the actual time was only about 4 seconds.

The system used by Xu Qiu is different from hers, so it can only be used as a reference, and the conditions need to be re-explored.

However, Wu Feifei counted the time in her heart, which was a little rough.

Xu Qiu had an idea and thought of a good way.

He can connect to the simulation laboratory while experimenting in reality, and use the stopwatch inside to time.

…………

Xu Qiu began to try, starting with the 1# solution.

For the first experiment, he set the stopwatch to count down to 5 seconds, and then simultaneously pressed the start button of the glue homogenizer in reality, and the stopwatch button in the simulated laboratory.

After the second count returned to zero, he quickly squeezed the toluene solvent in the pipette onto the surface of the substrate.

Because of his previous spraying experience, he has a very good control over the fineness of this step.

After spraying toluene, it can be clearly seen that some changes have taken place on the surface of the film, but because the substrate is still in the process of high-speed rotation, its specific shape cannot be judged.

After 30 seconds, the substrate stopped rotating, and Xu Qiu picked it up with tweezers.

Unfortunately, the resulting film still appeared as a white haze, but it was slightly better than without anti-solvent.

It appears that the addition of anti-solvent does work, but conditions still need to be improved.

Xu Qiu changed the interval to 6 seconds and tried again.

This time the white mist on the obtained film deepened, and it seemed that the interval should be shortened rather than extended.

Continue to adjust the interval time to 4 seconds.

This time, a film with a smooth and substantially uniform surface was finally obtained.

Since the spin coating method of the perovskite material used is not a spray coating method, about 80 microliters of solution will be consumed each time. If you try a few more times, the solution will be used up.

Therefore, Xu Qiu did not continue to fine-tune the interval time.

Although perovskite materials are not expensive compared to organic polymer materials, they are small molecules with relatively simple structures and are easy to synthesize.

However, lead iodide with a purity of 99.99% costs about 100 yuan per gram, so it cannot be easily wasted.

Next, he explored solutions 2#, 3#, and 4# respectively, and the optimal intervals for adding anti-solvent were all distributed between 3-6 seconds.

After exploring the conditions, Xu Qiu prepared to make a batch of devices.

The problem faced at this time is the choice of device structure.

One is the positive structure, which is to use perovskite materials to replace PEDOT:PSS, and the other is the inverted structure, which is to replace zinc oxide.

The two structures cannot be evaporated together, so only one structure can be done at a time.

He can't judge which structure is better to use now, so he will try the positive structure first.

…………

Clean the substrate.

Spin coat the transfer layer.

PEDOT:PSS substrate was used as a control group, and three slices were spin-coated;

1# to 4# solutions, each group also spin-coated three pieces, the concentration is 10% by mass fraction of DMF solution, the speed is 2000, 3000, 4000r.p.m. Used, as the experimental group A;

Do not spin-coat the transfer layer, make a piece, as the experimental group B.

After that, Xu Qiu spin-coated the PTB7-TH:PC[70]BM effective layer according to the optimal conditions, and evaporated calcium and aluminum electrodes.

start testing.

He first tested the benchmark system, a sample based on PEDOT:PSS.

The highest efficiencies of the three samples were 9.88%, 10.12%, and 9.63%, respectively.

Although the efficiency value fluctuates, the range is still within the acceptable range.

Next came the test of experimental group A, and he picked up the "1#, 3000r" sample with great anticipation.

For the first scan, the efficiency is 2.66%.

Continue to scan, the efficiency is getting lower and lower, and finally stabilized at 2.50%.

Xu Qiu shook his head and changed to a "1#, 4000r" sample.

The highest efficiency is 2.74%, which is a bit higher than the first one, but it is not useful.

Replace the last piece of 1# sample.

The highest efficiency is only 1.76%.

"Maybe the 1# sample is not good enough, other numbers may have miracles." Xu Qiu comforted himself in his heart.

But then, the more he thought about it, the colder he became.

None of the remaining 2#, 3#, and 4# samples had an efficiency exceeding 5%.

The sample with the highest efficiency is "4#, 4000r", but it is only 4.68%.

Finally, he tested samples from Experimental Group B, devices that were not coated with the transport layer material.

The efficiency is actually 5.52%, which is higher than that of all experimental group A.

This shows that after the perovskite material is coated, it has no positive effect at all, and it also lowers the performance of the device.

…………

After the test, Xu Qiu checked the time, and it was already past eight o'clock in the evening, and there was no time to make another batch of devices.

After working for a whole day, but with no results, Xu Qiu returned to his desk in frustration.

"How is it? Didn't the experiment go well?" Chen Wanqing asked with concern.

"Yes, the highest efficiency is only 4.68%, and the standard sample is 10%," Xu Qiu said depressedly:

"The most important thing is that the efficiency of no transmission layer is 5.52%."

"What about the structure of the device?" Chen Wanqing asked.

"Positive structure, to replace PEDOT, I used four kinds of perovskite materials, but none of them worked." Xu Qiu said:

"Well, could it be that they are not suitable for hole-transporting layers? You can make an inverted structure and let them replace zinc oxide to see how it works." Chen Wanqing said:

"Okay, then I'll try tomorrow." Xu Qiu said.

…………

On the way back to the dormitory, Xu Qiu thought over and over about today's experiment process, whether something went wrong.

It stands to reason that the four perovskite materials he chose have a wide band gap, and the morphology of the coated film is also good. Why is the result so poor?

He recalled the experiment process carefully, and suddenly discovered a detail that he had overlooked before.

"I understand!" Xu Qiu couldn't help shouting.

This roar shocked the hugging young couple on the bench next to them and separated them.

Xu Qiu made an apologetic gesture to them, and then quickly ran back to the dormitory, ready to verify it.

Thank you Lanzang Wenyuan for your 100-point reward.