Chapter 19: New buddy

　　 Back to the bedroom, only Ren Bin was there, but Tao Yan didn't know where he was going.
　　 Seeing Ren Bin still playing games, Xu Qiu walked up to him and stretched out his hand.
　　 Ren Bin wondered: "Xu Qiu, what are you doing?"
　　 "What do you mean?" Xu Qiu asked back.
　　 Ren Bin suddenly thought of what he had said after class in the morning, and said with a sad face:
　　 "Well, the last round."
　　 After the game is over, Ren Bin unplugged the keyboard and mouse from the main computer with a reluctant expression and handed it to Xu Qiu.
　　 "No more spares?"
"Have……"
"take it out."
　　 Xu Qiu found an empty wardrobe, put two sets of peripherals in, and then locked it.
　　 He threw the key on his desk and said, "If you want to play, get it yourself."
　　 "Don't want to seduce me, I have made up my mind again." Ren Bin grabbed the key and walked to the window. Seeing no one was around, he threw it out.
　　 Xu Qiu smiled and shook his head and said, "Fortunately, I have spare keys, otherwise you will have to hire a locksmith if you want to take them out again."
　　…………
　　 Sunday, the laboratory.
　　 When Xu Qiu arrived, he found that it was much more lively than usual.
　　 Including Chen Wanqing's senior sister, there are three women and one man sitting around the desk.
　　 One of the elder sisters is looking at the PPT on the computer, making a speech, speaking very fast.
　　 Xu Qiu guessed that she was Tian Qing who was about to participate in the defense of graduation.
　　 After confirming her identity, the identities of another man and woman are also ready to be revealed-Duan Yun and Wu Feifei respectively.
　　 After Chen Wanqing saw Xu Qiu, she opened the office chair next to her and waved at him.
　　 Xu Qiu understood her, walked to her and sat down, and listened to Tian Qing's speech with others.
　　 He can still understand the general content:
　　Tariharu used two methods: time-of-flight TOF and linear carrier booster CELIV to study the charge transport mechanism in the benchmark organic solar cell device based on P3HT:PC[60]BM.
　　 However, the specific analysis process and experimental details are not understood.
　　 It was an illustration in the PPT that attracted his attention.
　　 The illustration is hand-painted. In the picture, a girl is wearing a lab coat, wearing goggles, and operating two instruments. TOF and CELIV are also marked next to the instruments.
　　 Maybe Tian Qing painted it herself, Xu Qiu thought.
　　 The time for the undergraduate defense is generally short, and Tian Qing finished her speech soon.
　　Wu Feifei stopped the mobile phone stopwatch and said, "It takes nine and a half minutes, and the time is well controlled."
　　 "That's good. Our requirement is ten minutes to give a speech and five minutes to ask questions." Tian Qing paused and said, "What do you think of what I'm talking about? Do you have any questions?"
　　 Everyone looked at each other, but no one answered.
　　 "Okay." Tian Qing helplessly spread his hands.
　　 She noticed Xu Qiu, and took the initiative to walk towards him, and said, "Are you a new student?"
　　 "Yes, hello Tian Qing-senpai, I am Xu Qiu, a junior in material chemistry, and I just applied for a graduate student." Xu Qiu said.
　　 Tian Qing smiled and said: "Do you know who I am, did Teacher Wei mention me to you?"
　　 "Well, the first time I came, Teacher Wei told me about you." Xu Qiu said.
　　 Tian Qing covered her mouth and smiled: "Really."
After 　　 sent Tian Qing away, Xu Qiu greeted Wu Feifei and Duan Yun respectively, but both of them were busy, so they only responded politely to Xu Qiu.
　　 Duan Yun looks about 30 years old, with slightly dark skin, wearing a plaid shirt and shorts, like a person who has experienced ups and downs, with a little sense of vicissitudes.
　　 Wu Feifei dressed up as a student, staring at the computer screen intently, tapping the keyboard with both hands quickly.
　　 Suddenly, there was a sound of leather shoes "Da Da Da" from the corridor, and Xu Qiu saw the senior sister next to him subconsciously straighten up.
　　 Xu Qiu looked up, and it was Teacher Wei who came.
　　 "It's all here," Teacher Wei glanced around, and then asked one by one: "Wu Feifei, how have you changed it, show me how."
　　 Wu Feifei did not lift her head, still operating the computer quickly, and said, "It will be done soon."
　　 "Okay, you will come to me after you change it. Tian Qing, how are you preparing for your defense?"
　　 "I told them just now, I think it's ok."
　　 "Okay, I will help you after reading Feifei Wu's article."
　　 "Okay." Tian Qing nodded.
　　 Wei Xingsi looked at Duan Yun and Chen Wanqing: "You two articles should also be written quickly."
After 　　 got the response from the two, he finally turned to Xu Qiu:
　　 "Xu Qiu, are you still used to it here?"
　　 "I feel pretty good here." Xu Qiu said.
　　 Wei Xingsi nodded in satisfaction, turned and left.
　　 Not long after, Wu Feifei unplugged the U disk and walked towards the next 218 office.
　　 Tian Qing kept flipping through the defense PPT, while Duan Yun was immersed in the codewords.
　　 Xu Qiu found the senior sister and asked, "What did the experiment say today, how to apply the effective layer?"
　　 "Just use the six bottles of solution you prepared for me before, and I will write it to you if possible." Chen Wanqing said and wrote, and then handed the written note to Xu Qiu.
　　 She went on to say: "I will teach you evaporation after painting. This time I will mainly help me supplement data and do repeated experiments on device performance."
　　 "Okay." Xu Qiu said.
　　 He also learned from the literature that the so-called repetitive experiment refers to:
　　 Use the same experimental conditions to repeat an experiment to obtain multiple sets of experimental data. After removing the abnormal data, calculate the average value, extreme value and standard deviation of the remaining data as the final data.
　　This can effectively prevent the experimental data from being distorted due to accidental circumstances, and avoid false experimental conclusions.
　　 Like in the field of organic solar cells, the most important performance index is the photoelectric conversion efficiency of the device.
　　 So we have to make many batches of battery devices, and then give the highest efficiency, average efficiency and standard deviation. UU reading www. uukanshu.com
　　 The higher the grade of the journal, the higher the reviewers' requirements for repetitive experiments, which will require 10, 20 or even more repetitions.
　　…………
　　 After completing the protection work, Xu Qiu transferred the two boxes of substrates made on Friday into the glove box.
　　 For the two substrates coated with PEDOT and zinc oxide, the operation of spin-coating the effective layer on them is the same.
　　 Xu Qiu first checked the six previously prepared solutions and found that they all dissolve very well and can be used directly.
　　 Then he took a piece of substrate, took 60 microliters of solution with a pipette, and dropped it on the center of the substrate.
　　Start the homogenizer, the condition is 1200r.p.m., 60 seconds.
　　Remove the coated substrate, put it into a new petri dish, close the lid and wait until the surface of the substrate turns black, then put it back in the original petri dish.
　　This step is solvent annealing, using the residual solvent after spin coating to induce the crystallization of the polymer in the film, thereby improving the microscopic morphology of the film.
　　 Next, heat annealing at 130 degrees Celsius for 20 minutes.
　　 Then, wipe the tablet with chloroform solvent.
　　 Finally, make a mark on the back edge of the substrate, such as: "1:1:0, 1200r", "1:0.4:0.6, 1200r" and so on.
　　 These experimental operations are already written on the sticky notes by the senior sister, so he does not need to think, just follow them.
　　 If he conducts experiments on his own in the future, he must consider all the experimental details:
　　 For example, whether the pipette takes 60 microliters or 70 microliters of solution at a time; the spin coating speed is 1200, 1000, or 1500r.p.m.; the concentration of the solution is 20 or 24 mg/ml, etc.