Chapter 46: Drawing

　　We can make another batch of devices in the rest of today.
　　 However, only 200 microliters of 23 mg/ml solution was prepared yesterday, which may not be enough.
　　 So, after lunch, Xu Qiu made up another milliliter of the solution.
　　 After preparing the solution, he first etched 12 PEN substrates, then spin-coated PEDOT:PSS on the substrates, and then transported the substrates into the spin-coating glove box.
　　 At this time, Feifei Wu was using the glove box. Seeing Xu Qiu stuffing a petri dish into the transport cabin, she asked:
　　 "Are you going to spin coating? How long will it take?"
　　 "About half an hour, I don't need to be annealed, I just need to apply it and wipe the film." Xu Qiu said.
　　 "Okay, then you use it first." Wu Feifei left the glove box.
　　 "Wait a minute," she saw Xu Qiu entering the glove box, intending to spin-coat directly, and stopped:
　　 "I just finished applying the perovskite material. You'd better clean the glove box before you make organic devices."
　　 "Cleaning?" Xu Qiu asked in confusion.
　　 "This cleaning is not washing with water, but using nitrogen to clean the atmosphere in the glove box," Wu Feifei explained:
　　"During the spin coating process, the solvent in the solution will volatilize into the glove box.
　　 The main solvents we use to make perovskites are DMF and DMSO, which are polar solvents, while the chloroform and chlorobenzene used in organic devices are relatively less polar solvents.
　　 These two types of solvents can be said to be mutually anti-solvents, 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 unfavorable.
　　 In short, if you want to ensure the repeatability of the device you make, it is best to clean the glove box every time before spin coating the effective layer. Three to five minutes is enough.
　　 Does Chen Wanqing teach you how to clean it? "
　　 "No, she probably forgot about it." Xu Qiu recalled it carefully and said.
　　 "I'll teach you." Wu Feifei said: "I can use the pressure relief valve."
　　 "It will." Xu Qiu said.
　　 "First of all, adjust the pressure reducing valve of the nitrogen cylinder to the 3 position, which is usually 5 when we use it normally."
　　 Xu Qiu adjusted the pressure relief 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, it's all right."
　　 Wu Feifei explained while operating.
　　 After Wu Feifei pressed start, there was a "bang" in the glove box, and it seemed that a certain valve had been opened.
　　 Then, there was a "hiss" venting sound, and the two rubber gloves slowly expanded as the pressure inside the box increased.
　　 "Will this be a problem due to excessive pressure, such as opening the safety valve on the top of the box." Xu Qiu asked.
"No, this is a set program. The nitrogen bottle continues 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 Feifei said.
　　 "The direct emission of exhaust gas will cause pollution, right?" Xu Qiu asked.
　　"The amount of exhaust gas we produce is very small, so it is not practical to devise an industrial-grade exhaust gas treatment system, and the glove box is equipped with a filter and a condensation device, which can leave most of the solvent.
　　 Human beings want to live a better life, and there are some costs that must be paid, just as people know that burning coal and gasoline will cause excessive carbon dioxide emissions and cause the greenhouse effect, but they will still be used.
　　 After the cleaning is over, adjust the pressure reducing valve of the nitrogen cylinder back to 5 positions, open the circulation system, and you can start the normal experiment. "Wu Feifei said.
　　…………
　　 After cleaning, Xu Qiu continued to spin coat the effective layer.
　　 This time, he has 12 substrates.
　　 So he designed 6 groups of speeds, namely 1800, 2000, 2200, 2500, 2700, 3000r.p.m., each group of 2 speeds.
The 　　 solution is 23 mg/ml, PTB7-TH:PC[70]BM solution with a mass ratio of 1:1.3 to the receptor, 0.7% volume fraction + chlorobenzene solvent.
　　 Next, vapor deposition and test.
　　 Xu Qiu first picked the 2500-speed device that he thought might be the most efficient, and started testing.
　　 The first film, the highest is 7.89%.
　　 The second film, the highest 8.12%.
　　 The remaining ten slices, he quickly finished testing, and no more efficient battery devices appeared.
　　 After copying the data, Xu Qiu found Chen Wanqing and said:
　　 "Sister, my efficiency is 8%."
　　 "It's so smooth, then you can go to Teacher Wei to report the results," Chen Wanqing thought for a while and said: "He should say that you should write the article first, and I will go over with you."
"Ok."
　　…………
　　 The two came to the 218 office.
　　 Wei Xingsi sat on the swivel chair at the desk and said:
　　 "Let's talk, what's the matter."
　　 "8% efficiency, flexible substrate devices made by Xu Qiu." Chen Wanqing said.
　　 "Good!" Wei Xingsi patted the table, stood up, and said while pacing in the room:
　　"Xu Qiu, with this efficiency, the article can be written, first in Chinese, it can be used as a project closing report, and then translated into English.
　　 You start with the main text, and write out the description of each characterization. If any characterization is missing, take the time to make up for it, and get 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.
　　 "That's right, EQE tested it yet." Wei Xing thought.
　　 "Not yet." Xu Qiu shook his head.
　　 "Then wait for the EQE test first, the device may be inaccurate after a long time." Wei Xing thought for a while, and said:
　　 "By the way, after a few days of light source testing, Chen Wanqing, please take Xu Qiu with you. UU reading www.uukanshu.com"
　　 "Hmm." 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 them.
　　…………
　　 After returning, Xu Qiu tested the EQE curve of the best device this time and yesterday's P3HT device.
　　 Then, he went to the desk, turned on the computer, and prepared to draw the EQE and J-V curve.
　　 It turned out that he did not have the origin software, so he asked Chen Wanqing:
　　 "Senior sister, I haven't given me the original template that I said before, and where can I download the software?"
　　 "The school has free legal resources, just download them directly from the campus network, in the application of legal software."
　　 Chen Wanqing copied the template, handed the USB flash drive to Xu Qiu, and said, "Will the software be used."
　　 "No." Xu Qiu shook his head.
　　 "Then I will teach you some basic functions. Origin is very powerful, but we don't need most of them." Chen Wanqing said:
　　"Copy data directly from EXCEL or TXT text to the data table of origin software. The top of the data table will indicate whether this 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 compare multiple J-V curves in one graph, you can insert a Y axis on the data side, let them share the same X axis, then select them together, and then plot it. "
　　 Xu Qiu tried to do it by himself and finished the two pictures.