Polyethylene Glycol (PEG), with the chemical structural formula HO(CH2CH2O)nH, is prepared through a stepwise addition reaction of ethylene oxide and water or ethylene glycol as raw materials. Its raw materials are mainly derived from petroleum products. Those with a relative molecular weight of 200-600 are liquid at room temperature, while those with a relative molecular weight of more than 600 gradually become semi-solid. As the molecular weight increases, it changes from a colorless and odorless viscous liquid to a waxy solid, and its hygroscopic capacity decreases accordingly.
Polymer/Macromolecule Product List
| CAS | Product Name | Inquiry |
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With the rapid development of perovskite solar cells, organic cation-based perovskites cannot further improve their photovoltaic performance through higher intensity illumination due to their poor heat resistance, especially the stability under high light intensity. In order to further improve the photoelectric conversion efficiency of CsPbBr3 perovskite solar cells, improving their crystal quality is an effective research method. For example, in a two-step crystal preparation process, each step can be adjusted separately.
A research team has greatly improved the crystal properties of the wide-bandgap semiconductor CsPbBr3 perovskite by taking advantage of the crystal etching effect of PEG on PbBr2 and the strong penetration of PbBr2 by CsBr aqueous solution. This work improved the PCE of all-inorganic p-MPSCs based on CsPbBr3 to more than 10% for the first time, reaching 10.04%. Taking advantage of the excellent heat resistance of CsPbBr3 and the thermal conductivity of the thermoelectric TEG module and its ability to convert thermal energy into electrical energy, a high output power density of 28.35 mW cm-2 can be achieved. This opens up a new way to improve the preparation process of high-performance CsPbBr3 crystals and assemble all-inorganic stacked devices with high output power and high stability.
The research team first introduced polyethylene glycol (PEG) as an additive into the PbBr2 precursor. Using Fourier transform infrared spectroscopy (FTIR), they found that after the introduction of PEG, the C-O stretching vibration peak of PEG in the PbBr2 crystal moved to a higher wave number, indicating a strong interaction between PEG and PbBr2. In the Raman spectrum, the peak of the PEG+ PbBr2 sample curve at 144 cm-1 can be attributed to the existence of Pb-O bonds, indicating that Pb2+ in PbBr2 can interact with O in PEG. Selecting the ethylene glycol monomer and PbBr2 system for density functional theory (DFT) calculations, it can be obtained that the binding energy of Pb2+ and O in the molecule is -94.56 kcal/mol.
The test results of the relationship between the open circuit voltage VOC and light intensity and the open circuit photovoltage attenuation curve of the prepared p-MPSCs device once again show that the participation of PEG and water is beneficial to the smooth transport of photogenerated carriers in the device. Based on the improved PEG and water treatment process, the p-MPSC device achieved a photovoltaic performance of 10.04%. The monochromatic incident light photoelectric conversion efficiency and the device's steady-state current and efficiency output tests at the maximum power point further confirmed the accuracy of the J-V test results. In addition, PEG and aqueous solution treatment to obtain CsPbBr3 with better crystallinity will also help improve the thermal stability and long-term stability of the device.
When a solar cell is exposed to light for a long time, the surface temperature can rise significantly. This will not only cause a waste of energy, but the accumulation of heat will also accelerate the decomposition of the perovskite and affect the life of the device. In order to effectively reduce the surface temperature of the device and recycle energy, the research team connected a thermoelectric TEG module in series at the bottom of the p-MPSC device, using the temperature difference between the high-temperature end at the top and the low-temperature end at the bottom to generate electricity. The open circuit voltage of the series device can be significantly increased from 1.56 V to 1.75 V, and its PCE performance is also improved to 11.27%. At the same time, taking into account the good high temperature tolerance of CsPbBr3, the research team added a concentrator on the top of the device to further increase the output power density (Pout) of the stacked device of the series-connected p-MPSC-TEG module.
