Chapter 31: Instruct senior sister

　　 It was more than ten o'clock when Xu Qiu returned to the bedroom.
　　 It's another day in the shower.
　　 Xu Qiu thought about the project while taking a bath.
　　 When the senior sister gave him the project materials, he was stunned.
　　 There is nothing but an opening report, and the experiment progress is 0.
　　 The title is "Preparation and Performance Characterization of Organic Solar Cell Devices Based on Flexible Substrate".
　　 He needs to find literature, design experiments, conduct experiments, and write reports by himself.
　　 However, after the project is completed, it can be directly used as a graduation project, and it can also be used for labor fees of two thousand yuan, which is still a steady profit.
　　Of course, it is estimated that he will have time to start this project after the summer vacation. Now he still has a lot of things to deal with, such as spray painting, exams, and summer camps for research students...
　　…………
　　 Wednesday afternoon, the laboratory.
　　 "Xu Qiu, you are finally here." Chen Wanqing said: "Come and teach me spraying."
　　 "Senior sister is so anxious, I haven't made the zinc oxide substrate yet." Xu Qiu said.
"I'm going to apply a set of glass sheets first, and measure the UV-vis, which is the light absorption performance of the film. I guess the spraying method may improve the crystallization properties of the polymer inside the film. I want to take a look at its light absorption spectrum first. "Chen Wanqing said.
　　 "Yes, less than a day has passed, you have found the reason for the improvement of device efficiency." Xu Qiu said.
　　 "It's just a guess." Chen Wanqing said.
　　 "Okay, come on." Xu Qiu said.
　　……
　　 This time, Chen Wanqing entered the glove box, and Xu Qiu guided outside.
　　 The glass pieces are also cleaned before spin coating, but Xu Qiu washed a lot during spraying last time, so there are dozens of pieces in stock in the glove box.
　　 Xu Qiu saw that a petri dish was upside down on the heating and stirring table, and six bottles of solution were inserted in the bottle holder above.
　　 He noticed that the handwriting on the bottle was Chen Wanqing's, and curiously said: "When did the senior sister prepare the solution, I didn't find it."
　　 "After I went back last night, I have been thinking about your spraying method and what caused the efficiency increase. Later, I guessed that it was the cause of polymer crystallization, so I wanted to verify it today," Chen Wanqing said:
　　 "But all the dichlorobenzene solvents were prepared before, so I returned to the laboratory last night to prepare these six bottles of solutions and the chloroform solvent used."
　　 "Then the experiment is finished, it's not after 12 o'clock in the morning." Xu Qiu said.
　　 "Yes, but I don't have enough talent for experimentation, so I can only get it together by hard work." Chen Wanqing said.
　　 "At least the senior sister's talent in theory and data analysis is not bad." Xu Qiu comforted.
　　 "Hey, I think so too." Chen Wanqing smiled, and then started the experiment.
　　 She clamped the glass sheet, placed it on the platform of the homogenizer, and adjusted the speed.
　　 "Xu Qiu, what do you think is the right speed?"
　　 "2000, I haven't made a device yet, and I don't know how much it is appropriate."
　　 "Okay, then 2000."
　　 Then, she mounted a pipette tip on the pipette gun and cut the tip into two with a click with scissors.
　　 One section is still on the pipette, but the other section is missing.
　　 "Senior sister, did you cut the head like this?"
　　 "Didn't you teach me to cut in between, is there any problem?"
　　 "The section on the pipette is fine and can be used directly, but what about the other section?"
　　 She rummaged in the glove box for a while, finally found another section on the reagent rack, picked it up and threw it into the trash bag.
　　 "Sister, when you cut it, don't use too much force, or it will fly far."
　　 "Yeah." Chen Wanqing nodded.
　　 Next, she sucked the solution, pressed the start button, and sprayed the solution from the pipette gun.
After 　　 was over, it was found that half of the area on the substrate was not coated, and the coated part was still layer by layer.
　　 "Ah, how could this happen." Chen Wanqing looked at Xu Qiu with a plea for help.
　　 Xu Qiu is a little bit painful in his head, and analyzes her operation problems to the senior sister one by one:
　　"First, it takes about 1 second for the homogenizer to accelerate from static to 2000 speed, so wait for it to stabilize at 2000r.p.m. before spraying the solution;
The second point is to quickly spray the solution from the pipette at one time, otherwise it will cause the layering of the film. Imagine a high-speed rotating substrate on which the solution will form a film quickly, but slowly Spraying out the solution is equivalent to spraying the solution multiple times to form a multilayer film;
　　 The third point is that when spraying the solution, the hand holding the pipette gun should not be shaken. Excessive shaking will also cause multiple film formation, resulting in delamination;
The fourth point is the position and angle of the pipette tip. The angle should be 45 degrees to the substrate. The position is not easy to describe directly. Then, sister, you can pick up the pipette and I will guide you in real time. . "
　　 Chen Wanqing picked up the pipette gun, Xu Qiu began to instruct:
"Get a little bit forward, then a little bit forward, ok, stop, keep a little bit to the left, keep it to the left instead of the right, ok, stop, then the angle is wrong, this is almost 60 degrees, press down a little bit, ok, just this Position, keep it for thirty seconds."
　　 30 seconds later.
　　 "Have you learned, Sister." Xu Qiu said.
　　 "Probably, I have lost my studies," Chen Wanqing said.
　　 "Let's go ahead and check the results." Xu Qiudao~EbookFREE.me~ OK. "
　　 The first piece is slightly flawed, about one-fifth of the area is not spin-coated.
　　 "Throw it away." Xu Qiu said.
　　 "Why, the light metering absorption performance does not need to be covered completely." Chen Wanqing asked.
　　 Xu Qiu did not speak.
　　 "Okay." Chen Wan said weakly, picking up the glass and throwing it into the garbage bag.
　　 The second piece, N-layer film.
　　 throw it away.
　　 The third piece, double-layer film.
　　 throw it away.
　　 The fourth film.
　　 "This film seems to be no problem." Chen Wanqing said a little excited.
　　 "You take a closer look." Xu Qiu said with a glance.
　　 "Wait, this is not a glass sheet, but an ITO substrate." Chen Wanqing put on an aggrieved expression, and then threw it into the old substrate box.
　　 On the fifth piece, about a quarter of the area was not spin-coated.
　　 throw it away.
　　……
　　Senior sister made various mistakes like this.
　　 Xu Qiu was anxious outside the glove box, wishing to get started directly, doing experiments with the teaching sister hand in hand, but there was a thick layer of explosion-proof glass blocking it.
　　 He suddenly understood the mood of Teacher Wei when he was teaching his sister.
　　 Fortunately, after scrapping more than 20 glass sheets and adding an ITO substrate, the sister finally succeeded in continuous spraying and obtained six sets of relatively perfect film samples.
　　 "Senior sister, you are almost using up the glass sheets I washed before." Xu Qiu vomited.
　　 "Hmm...at least the result is good," Chen Wanqing said embarrassedly: "Wait for me to test UV-vis, do you want to come and learn?"
　　 "Well, wait for me, I will clean the substrate first." Xu Qiu said.