I Have a Research Support System

　　 "Next, let's check the results of the younger brother." Chen Wanqing said.

　　 "Sister, don't worry, it will be fine." Xu Qiu was confident.

　　 "Okay, then I will wait and see," Chen Wanqing said: "Teach you how to test first."

　　 Following the guidance of the senior sister, Xu Qiu looked at the set of instruments on the right side of the evaporation machine.

　　 a computer, a box with a digital display panel, a component integrated with eight probes, and a black cover;

　　 The most conspicuous is a searchlight-shaped hemisphere embedded in the bottom of the glove box, and the nameplate next to it is marked "Sol3AAAA, 94043A solar simulator".

　　 Chen Wanqing did not rush to introduce the instrument, but started from the principle:

　　"The test process, in simple terms, is to illuminate the battery device with simulated sunlight.

　　 During this period, a linear voltage sweep is used to obtain the curve of the current density with the voltage, that is, the J-V characteristic curve.

　　 Through the J-V characteristic curve, the short circuit current density Jsc, open circuit voltage Voc and fill factor FF of the device can be calculated.

　　 In addition, there is also the input power density. We simulated the AM1.5G condition, that is, the average illuminance of sunlight incident on the earth's surface. The specific value is 100 milliwatts per square centimeter.

　　 Finally, through the formula, the photoelectric conversion efficiency (PCE) of the device is equal to Jsc*Voc*FF/input power density. "

　　 These physical quantities, Xu Qiu has seen in the review before, so they are not unfamiliar, but this is the first time I have seen the simulated light source.

　　 He wondered: "How do you know this light source, it simulates the intensity of a sunlight?"

“At first use, the light intensity will be calibrated with standard silicon cells,” Chen Wanqing explained: “However, after long-term use, the light intensity will decline, so it needs to be re-calibrated every once in a while, otherwise the test results It will be lower."

　　 Chen Wanqing continued: "It has two switches, one is the master switch and the other is the light control switch.

　　 Turn the main switch, that is, the red button from 0 to 1, and let it warm up first. It usually takes ten minutes to warm up. During this time, I can introduce you to other parts. "

　　 Xu Qiu turned on the main switch, and a "whooping" sound came from the inside of the instrument, as if a fan was operating.

　　 "Sister, do you want to turn on the computer?"

"Yes."

　　 Xu Qiu entered the glove box and pressed the computer's power button.

　　 The familiar XP system boot screen is loading.

　　 After waiting for ten seconds, the computer desktop with blue sky and white clouds appeared.

　　 But the above is clean, except for "My Computer", there is only one software, the name is "Madu Comprehensive University Physics Laboratory".

　　 "Is it this software?" Xu Qiu moved the mouse over.

　　 "Yes, this is what Teacher Wei wants from the Physics Department. They wrote it in LabVIEW." Chen Wanqing said.

　　 Xu Qiu opened the software and found that the interface of the software was very concise without any fancy things.

　　 The upper left is the parameter setting area, and the lower left is the image display area. There are two horizontal and vertical axes, the horizontal axis is voltage, the unit is volts, and the vertical axis is current density, the unit is amperes per square centimeter;

　　 The upper right is the test result display area, including Jsc, Voc, FF, PCE, and the lower right is the dark state compensation, start and stop buttons.

　　 The parameters have default values, which are basically set.

　　 The initial scanning voltage is -1 volt, the maximum voltage is 1 volt, the scanning interval is 0.01 volt, the battery area is 0.09 square centimeters, the dark state compensation is 0, and the current test condition is dark state.

　　 After getting familiar with the software interface, Xu Qiu looked at the box with the digital display panel beside the computer and asked:

　　 "Senior sister, what is this? Is it used to test the current?"

"It's very smart," Chen Wanqing said: "This is a Keithley 2400 source meter. It can provide a highly stable DC voltage. At the same time, it can pass the real-time test to 1 picoamp, which is the negative 12th power of ten amperes. "

　　 Xu Qiu presses the start button of the source meter. After a beep, the instrument starts, and the two digital display panels light up, displaying the current and voltage respectively.

　　 Then, he started to install the substrate.

　　 First took a piece of zinc oxide substrate labeled "1:1:0, 1200r", and placed the back of the substrate, that is, the glass side down, on the upper platform of the solar simulation light source.

　　 There is a groove on the platform, and the substrate can just be inserted into it, and it is directly above the hemisphere of the simulated light source.

　　 After the light source is turned on, the light can pass through the glass and irradiate the effective layer vertically to generate photoelectric conversion and generate photocurrent.

　　 Next, he took the component with eight probes and connected them with a bracket, with the probes facing down and pressed on top of the substrate.

　　 There are two sets of wires connected to the outside of the component, each set of wires is one black and one red, a total of four, which are connected to the Keithley source meter in a "four-wire method".

　　 Eight probes are parallel to each other, three on the left and one on the left and one on the top and the other.

　　 These probes can just be pierced on the edge of the battery device.

　　The six probes on the left and right are just tied to the end of the six sets of aluminum electrodes of the device, and the upper and lower probes are tied to the ITO electrodes.

　　 In fact, the ITO electrodes of the six batteries are shared, and only one probe is needed. However, for the sake of beauty and prevention of accidental breakage of the probe, it is designed to be two.

　　 Finally, Xu Qiu used a black cover to cover the solar analog light source together with the substrate and probe components.

　　 "Alright, ready to test," Chen Wanqing said: "The test is divided into two types, light and dark state. Generally, you need to test the dark state first, and then continue to test under light."

　　"Because in the dark state, the battery device will also generate a small amount of current. This part of the current is not generated by the light, so it needs to be deducted.

　　 Although under normal circumstances, even if it is not deducted, the impact on the results is not large, but in order to ensure the rigor of the results, this step cannot be omitted. "

　　 "Okay." Xu Qiu clicked the start button of the software. UU reading www.uukanshu.com

　　 "drop."

　　 The source meter starts to work, and the voltage value on the left is at 0.01 volt intervals, starting from -1 volt and increasing continuously;

　　 The current on the right started to be negative and only at the microampere level. After the voltage reached 0.64 volts, it turned positive and increased rapidly.

　　 The scan ends and the result is obtained.

　　 In the dark state, the short-circuit current density is only -0.0018 mA per square centimeter, and the photoelectric conversion efficiency is 0.0033%.

　　 After Xu Qiu clicks on the dark state compensation, the dark state compensation in the upper left corner automatically changes to -0.0033%.

　　 Seeing that the short-circuit current density is negative, he wondered: "Sister, why is this Jsc a negative value? The literature is all positive."

"This is caused by the test method. We provide a reverse bias voltage to the battery to offset the photo-generated current it generates. Therefore, the measured current is negative, which means that the current direction is opposite to the voltage direction. When the device actually works, it is just right." Chen Wanqing said.

　　 Xu Qiu nodded thoughtfully.

　　 Then, he changed the test condition of the software to the bright state and turned on the light control switch of the simulated light source.

　　 There was a "pop" sound, and a ray of light leaked from the bottom of the black cover.

　　 Xu Qiu clicks the start button, after the voltage is scanned, the bright state J-V characteristic curve is obtained.

　　 On the right side of the software interface, four photoelectric parameters are displayed. The short-circuit current density is -11.02 mA per square centimeter, the open circuit voltage is 0.65 volts, the fill factor is 0.60, and the photoelectric conversion efficiency is 4.30%.

　　 "Boy, awesome!" Seeing the results of the experiment, Chen Wanqing was a little excited and said, "The first time I made a device, I was successful."