Study On The Planar And Mesoscopic Perovskites Solar Cells

Nowadays, Organolead halide perovskites solar cells have been significantly concerned, due to its excellent photovoltaic performance and low cost, which is deemed to be the "rising stars" of photovoltaic industry. The highest certified efficiency has reached 20.8 % so far. And the momentum of research is exceptionally strong so that it has a great potential for development.This paper employed the perovskite-absorbed layer CH₃NH₃ Pb I₃?abbreviated as MAPb I₃? as the main raw material, and investigated preparation process and photoelectric performance of the planar heterojunction and mesoscopic perovskite solar cells.Firstly, the crystal structure and optical absorption properties of MAPb I₃ have been studied. The tetragonal MAPb I₃ perovskite single crystal was grown via the solution method, which showed integrated crystal morphology and diameter was about 7 mm. We also employed UV-visible diffuse reflectance spectra and calculated MAPb I₃ crystal band gap of 1.53 e V, which illustrated that MAPb I₃ crystals have a narrow band gap and a strong ability to capture light.The photovoltaic performances of perovskite-absorbed layer MAPb I₃ solar cells have been further investigated, MAPb I₃ perovskite thin films were prepared via the new one-step and by optimizing the preparation process assembled perovskite planar heterojunction solar cells. we investigated influences on MAPb I₃ thin-film structure and photovoltaic performances of the perovskite solar cells by different solution concentration and the number of spin-coating for compact TiO₂ layer prepareing and MAPb I₃ solution concentration for MAPb I₃ flim preparing. The photoelectric conversion efficiency of up to 11.34 % was achieved by using second spin-coating solution of 0.1 M Ti Ac Ac for the dense TiO₂ layer and 45 wt% MAPb I₃ solution for perovskite flim. Combined electrochemical impedance spectroscopy, the dark state JV with J-V curve hysteresis phenomenon test analysis, illustrate optimization of TiO₂ dense layer and perovskite layer can effectively improve MAPb I₃ film coverage, reduce pin holes and electron-hole recombination, thereby improve the photoelectric conversion efficiency.We employed the traditional and new two-step method to prepare the various morphologies of MAPb I₃ perovskite layer. Morphology and photovoltaic performance depending on deposition procedures of MAPb I₃ have been studied. Experiments show that the MAPb I₃ films vis new two-step process present high crystallinity, compact and orderly arrangement of the crystal, the completely substrate cover, which hindered HTM contact with TiO₂ mesoporous layer and restrained electron-hole pairs recombination and promot photo-generated electron transfer. while we optimizing the thickness of mesoporous TiO₂ layer, cells received the highest photoelectric conversion efficiency with a thickness of 403 nm flim. Parameters were Jsc=23.85 m A/cm2, Voc=1.01 V, FF=0.64, PCE=15.38 %.