Fabrication Technology And Performance Of Perovskite Solar Cells

Solar energy, as a clean and renewable energy, has become the promising alternative to fossil fuels. In recent years, perovskite solar cell ?PSC? has developed rapidly and it's power conversion efficiency ?PCE? has jumped from 3.8% to 20.1%. However, the research on PSC is still in its infancy. The charge transport mechanism inside the device and the key technology of fabricating high performance device are not yet fully understood. Therefore, this thesis focused on studying the technology of different PSC and the influencing factors on the cell performance. The specific research progress are as follows:1. We prepared perovskite layer on the mesoporous TiO₂ scaffold using two-step sequential solution deposition method. The mesoporous layer with different thickness from 200 to 400 nm were used to study the PSC performance. Therefore, the optimal thickness of mesoporous layer c.a.300 nm could load enough perovskite and provide suitable electron transfer length. Further, the thickness and coverage of perovskite layer were regulating by fine control of the deposition time. PbI₂ can be completety converted to perovskite CH₃NH₃PbI₃ in the deposition time of 40 s, leading to a thick perovskite layer with high coverage and large light absorption. With the increase of the deposition time, perovskite appeared to dissolve, resulting in a performance decrease in the photovoltaic cell device. Finally, At last, based on the mesoporous 300nm-thickness TiO₂ PSC prepared in 40 s deposition time, short-circuit current density and PCE were 21.3 mA·cm^-2 and 12.1% respectively.2. We prepared perovskite layer on ZnO film using the one-step solution deposition method, and then assembled into the plannar ZnO PSC. The thickness of perovskite layer can be controlled between 140 nm to 470 nm by spin coating a concentration of 30wt.%?50wt.% perovskite solution in DMF. We found the 300 nm thickness of perovskite layer prepared at a concentration of 40wt.% performed best. SEM showed its surface was smooth without holes, and PL demonstrated it had fewer crystal defects. We got a 12% PCE on the plannar ZnO PSC prepared by the concentration of 40wt.% perovskite solution in DMF. Further, we found perovskite had good crystallinity and exciton transport capabilities by annealing at 70 ?, but the high temperature ?80 ? above? will lead perovskite decomposition and the performance decrease of device. Finally, the device performance can be improved by regulating the oxidation time and the optimal oxidation time is 24 h. After the oxidation process, the fill factor and PCE of device can be increased to 0.7 and 13.1% respectively.3. Three kinds of ZnO were prepared by sol-gel ?s-ZnO?, complexometry ?c-ZnO?, precipitation ?p-ZnO? methods, and used as electron transport layer for PSC. SEM showed c-ZnO had a suitable particle size and surface roughness. Besides, steady state and transient PL indicated that c-ZnO had better electron transport properties, while UPS demonstrated c-ZnO had a lower work function of 3.69 eV that facilitated obtaining a high open circuit voltage device. Finally, a high open circuit voltage of 1.206 V and power conversion efficiency of 13.2% were achieved based on c-ZnO-PSC.