The Effect Of Halogenated Alkane Additives On Doping Density In Polymer Solar Cells And The Fabrication Of Perovskite Solar Cells

ABSTRACT:In polymer solar cells, film morphology plays an important role on the exciton diffusion, carrier separation and transportation in the devices, while the additive is one of common and effective means controlling and optimizing the surface morphology, but the impact on the internal mechanism of the devices is still not very clear. In addition, p-doping is discovered to be a key parameter determining the performance of polymer solar cells. The doping in PSCs is always unintentional and the nature of the doping is not clear. A high doping level always has a serious consequence on the photocurrent of the device and thus the efficiency. Recently, the development of perovskite solar cells is very fast, and the efficiency is approaching20%. Due to their advantages such as low-cost fabrication, solution-processable, excellent optical performances and high efficiencies, perovskite solar cells have attracted more and more attentions. However, there are some problems in the perovskite solar cells, such as poor stability of the devices, containing heavy metals and some ions in the devices. Moreover, the researches on the perovskite solar cells in recent years just stay in the procession stage, and the working mechanism is not yet clear, there are still some issues worth studying. Based on the issues raised above, this work summarizes the following sections:Firstly, the effect of halogenated alkane additives on the photoelectric properties of the organic solar cells is studied. By processing halogenated alkanes to the devices, and characterization of the devices, study the effect of additives on the absorption spectrum, charge mobility, p-type doping density and surface morphology of the layers. P3HT only and PCBM dominated devices were fabricated to further study the mechanism of additives on the devices.Secondly, perovskite solar cells were fabricated using one-step deposition, and the effect of the spinning speed of solution and the proportion of Pbl2to CH3NH3I on the performance and crystallinity of perovskite solar cells were studied. It’s found that with the higher spinning speed of solution and smaller proportion of PbI2to CH3NH3I, the higher coverage of the perovskite films, higher performance of the devices will be achieved.Thirdly, perovskite solar cells were studied using sequential solution deposition. The study found that the performance of Cl-doped perovskite cells was significantly better than the pure I perovskite cells. In addition, the impact of the thickness of the first layer Pbl2/PbCl2and the second layer CH3NH3I on the devices were further studied. Moreover, the annealing temperature, annealing time and PCBM thickness were further optimized, thereby producing high performance perovskite devices.