Device Optimization And Large-scale Fabrication Of Efficient Inverted Perovskite Solar Cells

With the continuous improvement of industrialization in various countries,the traditional fossil energy on the earth has been consumed in large quantities,so the development of renewable energy has become the focus of energy research.Solar cells convert light energy into electrical energy,which has the advantages of high energy conversion rate and easy storage.It is generally considered to be the best way to efficiently use solar energy.Among them,perovskite solar cells(PSCa)have attracted extensive attention from researchers because of their low cost,flexible manufacturing,and high conversion efficiency.Although currently the most efficient PSCs are mainly based on planar regular structure and mesoporous regular structure,the inverted structure has the advantages of simple preparation process and easy combination with traditional solar cells to prepare laminated devices,which opens up for future commercial production.Therefore,this paper will focus on the device optimization of inverted PSCs and expand to the preparation of large-area devices.The main work is as follows:We have developed new organic small molecule hole transport materials(HTMs)TMeOPSIDA and TMe PSIDPA.Compared to PEDOT: PSS,the HOMO energy level of TMeOPSIDA and TMePSIDPA is more closely matched to the valence band of perovskite,which is beneficial to the extraction of charge between interfaces and improves the open circuit voltage(VOC)of the device.Among them,TMePSIDPA has a higher hole mobility than TMeOPSIDA,which represents a better hole transport capability.From the SEM surface image,the perovskite thin film based on small molecular materials has a larger grain size.By optimizing the solution concentration and annealing temperature of TMeOPSIDA,the device performance is optimized to a power conversion efficiency(PCE)of 19.41%,and the stability test also proves that the device based on TMeOPSIDA can maintain a higher initial efficiency during the same storage time.The introduction of zwitterionic BTCC(bethanechol chloride)can attach to the surface of perovskite by forming hydrogen bonds and passivate various types of defects,including vacancies of MA ions and I ions and under-coordinated lead ion defects.The steady state PL and transient PL tests confirmed that BTCC can effectively passivate the defects in perovskite,suppress the non-radiative recombination of carriers and extend the life of carriers.By optimizing the mass ratio of BTCC to be 1%,the PCE of devices prepared based on PTAA reached 20.45%,and the pce based on the small molecule TMeOPSIDA HTM could reach 21.12%,further confirming the universality of this optimization process.In addition,the introduction of BTCC has greatly improved the long-term stability of the device.After BTCC treatment,the device still has 82% of the original efficiency after being stored in the ambient environment for 800 h.We adopt the doctor blade-coating method to realize the printing preparation of inverted-strcuture devices.Adding a suitable content of DMSO solvent to the precursor solution,due to its higher boiling point and coordination of lead ions,it is more difficult to remove from the solvent,which can play a role in delaying crystallization and regulating crystallization.By conducting J-V tests on devices based on different ratios of DMSO,we can find that when DMF: DMSO=8.5: 1.5,the overall device is significantly improved,and the PCE jumps from 10.98 to 13.83%.The device based on the inorganic NiO_x hole transport layer further improves the device efficiency to 15.34%.The most obvious improvement is the VOC,because the energy level of NiO_x and perovskite is more matched than that of PEDOT: PSS.Moreover,the good film wettability of NiO_x can further improve the utilization rate of the solution,which is very suitable for future largescale production.Combined with the optimization plan,we finally achieved the preparation of 10 cm×10 cm large-area modules with a PCE of 2.97% using the bladecoating method.