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　　 Xu Qiu disposed of the failed substrate and began to think about the reasons for the failure.

　　On the one hand, the etching time may be too long;

　　 On the other hand, there may be air bubbles between the tape and the substrate, or the gap between them is too large.

　　 Experiment again.

　　 Xu Qiu took three more PEN substrates, and after pasting the pattern with 3M electrical tape, he repeatedly pressed the area of ​​the tape with tweezers to make it fit the substrate as much as possible.

　　 Then, he added dilute hydrochloric acid to three new disposable plastic cups and poured two spoons of zinc powder.

　　 After waiting for five seconds, he put the three substrates into a plastic cup, and pressed the stopwatch at the same time.

　　 Every 40 seconds, remove a piece of substrate, then rinse it with deionized water, and tear off the 3M electrical tape attached to it.

　　 Xu Qiu observed by naked eyes that the substrates with etching time of 40 seconds and 80 seconds have obtained good patterns.

　　 On the substrate with an etching time of 120 seconds, the edges of the ITO pattern are corroded by acid, but compared to the previous experiment, the traces become less obvious.

　　 This shows that the adhesive tape is closely attached to the substrate, which plays a certain role in preventing the acid from penetrating under the tape.

　　 The naked eye may deceive people. In order to ensure the successful etching, Xu Qiu took out the multimeter from the toolbox and measured the conduction of the etched part on the substrate.

　　 Set the multimeter to the conduction mode. If the resistance between the two red and black test leads is very small, the multimeter will emit a beeping sound.

　　 After testing, the etched parts of the three substrates are all non-conductive, and ITO itself is a good conductor, which indicates that the exposed ITO was successfully etched.

　　 Therefore, the conditions of etching time of 40 seconds and 80 seconds are both feasible.

　　 Xu Qiu finally chose an intermediate value and etched for 1 minute.

　　…………

　　 After exploring the experimental conditions, Xu Qiu prepared 12 patterned PEN/ITO substrates.

　　 Although a piece of tape failed in the middle because the tape was not sticky, it did not affect the overall situation.

　　 Then, he cleaned the substrate with isopropanol, then dried it with a nitrogen gun, and put it into a petri dish.

　　 The next spin coating operation, Xu Qiu encountered new problems.

　　 The PEN substrate cannot be sucked firmly by the platform above the spreader. During high-speed rotation, the substrate sometimes flies out directly.

　　 Xu Qiu thought for a while, stuck the PEN substrate on a glass plate of the same size, and then spin-coated.

　　 Solve the problem smoothly.

　　 After applying PEDOT:PSS, Xu Qiu removed the glass sheet from the substrate, then annealed it at 100 degrees Celsius and wiped the sheet.

After 　　, he re-attached the glass sheet on the substrate and passed it into the spin-coated glove box.

　　 After Chen Wanqing saw it, she asked curiously: "Xu Qiu, what is this, is there a...PEN substrate on the glass?"

　　 "Yes, I have already found a way to etch the PEN substrate, wet etching, paste it with 3M tape, and control the time," Xu Qiu said:

　　 "A piece of glass is pasted to facilitate spin coating."

　　 "Okay, what effective layer are you going to apply later?" Chen Wanqing said.

　　 "Sister, give me some PTB7-TH solution for use, and tell me the spin coating method." Xu Qiu said.

　　 "There should be 500 microliters of the solution on the heating stirring table, enough for you to use," Chen Wanqing said:

　　 "As for the experimental conditions, I will write them down on a sticky note later and give it to you. It's about to have lunch now. Let's do the experiment when I come back after eating."

　　…………

　　 In the afternoon, before one o'clock, Xu Qiu took the senior sister's note paper and entered the glove box.

　　 There is no way, the spin-coated glove box is delicious. He is afraid that he won't be able to grab the right to use the glove box by one and a half.

　　 Xu Qiu glanced at the experimental conditions of the senior sister:

　　"Chlorobenzene solvent, 15 mg/ml, 1:1 ratio to the receptor, 2000 speed, 0.5% volume fraction, no annealing."

　　 can be used directly, only need to adjust the speed.

　　In the process of storage and use, the concentration of the solution will change due to the volatilization of the solvent.

　　 Generally, the longer the solution is prepared, the higher its concentration, and the higher the corresponding optimal speed.

　　 Therefore, in general, a solution will perform multiple speeds to compensate for the influence of the change in solution concentration.

　　 This time making the device is only a preliminary attempt, Xu Qiu did not intend to use up all the 12 substrates.

　　 He decided to use only four tablets, two of which were coated with PTB7-TH: PC[70]BM solution, and the other two with the previous P3HT:PC[60]BM solution.

　　 The two pieces of P3HT are slightly more complicated because they involve thermal annealing and solvent annealing.

　　 The annealing temperature needs to be controlled at 100 degrees Celsius, and the glass sheet attached underneath should be removed during annealing.

　　…………

　　 Put the four substrates that have been spin-coated into the evaporation chamber, prepare for evaporation, and start vacuuming.

　　 Xu Qiu saw that no one was using the spin-coated glove box for the time being, so he planned to prepare a solution according to the best conditions he had previously explored in the simulation laboratory.

　　 20 mg/ml, PTB7-TH:PC[70]BM solution with a ratio of 1:1.3 to the receptor, 0.7% volume fraction + chlorobenzene solvent, one ml.

　　As soon as the solution was finished, Xu Qiu was marking the bottle, and Chen Wanqing leaned in.

　　 "Are you preparing the solution, PTB7-TH?" Chen Wanqing asked.

　　 "Yes." Xu Qiu said.

　　 Chen Wanqing nodded, and did not ask more: "How long will you be better."

　　 "I'm fine, do you need my help?" Xu Qiu asked.

　　 "No need~www.ltnovel.com~ Let me do it myself, I want to prepare a solution of perovskite."

　　…………

　　 After Xu Qiu vaporized the calcium and aluminum electrodes, the device performance was tested.

　　 Picked up the first piece, which is based on PTB7-TH.

　　 efficiency is 6.77%.

　　 Not bad, this value at least shows that the battery device is working normally.

　　 Xu Qiu's psychological expectation for the efficiency of this device is more than 5%, because it is only a school project, just look at the past on the data, and there is no need to pursue high efficiency.

　　 After all, the original intention of the school project is mainly to cultivate students' scientific research thinking, and does not value the output of the results. Of course, if there are results, it is naturally good.

　　 The second film, the highest value was 6.92%, which was a slight increase, but it did not exceed 7%.

　　 Then, he tested two P3HT devices and the highest value was 4.13%.

　　 Generally speaking, compared with the glass substrate, the battery device performance of the PEN substrate has not deteriorated too severely.

　　 After all the tests are finished, it is already more than five o'clock. It is obviously too late to make another batch of devices today.

　　 At this time, Xu Qiu suddenly thought that the solution he had prepared was directly in accordance with the optimal conditions. It would be difficult to explain when it was used directly, so it needed to be disguised.

　　 came to the glove box, the person inside was Chen Wanqing.

　　 "Senior sister, I have come to prepare the solution," Xu Qiu said:

　　"I just read your experiment notebook, which does not control the concentration of the solution and the ratio of donor to receptor.

　　 I want to try to find the optimal conditions in this regard. I plan to prepare a few more sets of solutions, each with only 200 microliters, and it won’t cost too much raw materials. "

　　 "Okay, I'll be fine right away, wait five minutes for me." Chen Wanqing agreed directly without thinking.