| Organic-inorganic hybrid perovskites attracted great interest due to their superior properties,including large absorption coefficient,tunable band gap,long carrier diffusion length,high carrier mobility etc.The organic-inorganic hybrid perovskites have been extensively applied in the fabrication of solar cells,photodetectors,light-emitting diodes etc.In these devices,the quality of perovskite films dominated the generation,transportation and recombination process of the carriers.Thus,fabricating perovskite films with large crystallites,low defect density,high orientation,smooth surface and thorough boundary fusion is an effective route to improve the performance of the optoelectronic devices.Herein,by applying the synergestic effect of pressure,solvent and space-confinement,we developed some new strategies,including two-round pressure-assissted solvent-energining method and pressured-assissted high-temperature solvent-energining method.Furthermore,the overall quality of MAPbl3(MA=CH3NH3+)films was strikingly improved after being treated by these new methods,and the performance of the corresponding optoelectronic devices was also greatly enhanced.The main contents of this thesis include:(1)The pressure-assissted solvent-engeering(PS)strategy was developed for the post-treatment of MAPbI3 film fabricated by conventional one-step spin-coating method.By systematically optimizing the preparation parameters including pressure,solvent,space-confinement and the substrate,the crystalline perfectness of MAPbl3 film was greatly improved.(2)In order to futher improve the crystalline perfection of MAPbI3 film,a new strategy called two-round pressure-assissted solvent-energining(TPS)was developed.The MAPbI3 film treated by this method possesses high coverage,much larger crystals and completely fused grain boundaries.The photodector fabricated by using the TPS treated MAPbI3 film exhibites fast response(137/340 μs),very high on/off ratio(～106)and detectivity(1.3×1014 Jones).Furthermore,the detecting wavelength of the photodector was extended to near infrared region by incorporating up-conversion nanoparticles into the TPS treated MAPbI3 film,the resposivity and detectivity of the corresponding device reached 1.02 mAW-1 and 1.8×109 Jones under the excitation of 980 nm laser.(3)On the basis of the facilitating effect of high temperature on the migration of ions within the interfacial region,we developed a facile pressure-assissted high-temperature solvent-engineering(PHS)method by introducing high temperature into the treatment process of MAPbI3 film.By utilizing this new method,MAPbI3 qusi-single-crystalline film was fabricated on the SiO2/Si substrate.Due to the faster migration speed of the ions within the interfacial region under high temperature and high pressure(150℃&150 MPa),the grain size increased to as large as～100 μm and the grains boundary fused more completely.In the MAPbI3 film treated by PHS method,the density of defects decreased to 7.43×1011 cm-3 and the lifetime of the carriers increased 1.7 μs.Correspondingly,the performance of the photodetector fabricated from the treated MAPbI3 film was greatly improved,the on/off ratio reached to 2.4×106.(4)For eliminating the corrosion effect of solvent to the hole-transportation layer in solar cells,we introducing the high hydrostatic pressure and space-confinement effects into the treatment process of the complete solar cells,thus a much simpler hydrostatic hot-press(HHP)route was developed.Firstly,this HHP route was utilized in the treatment of MAPbI3 polycrystalline film fabricated using conventional anti-solvent method,thus MAPbI3 quasi-single-crystalline film with large grains,high crystalline perfectness and smooth surface was obtained.Furthermore,the invert structure p-i-n solar cell was prepared by using the HHP treated MAPbI3 film as the active layer,and investigated the relationship among the treating pressure,crystalline perfectness of the MAPbI3 film,the short-circuit current,open-circuit voltage and PCE of the solar cells.By fully optimizing the treating parameters,the average PCE of the HHP treated solar cell increased to 17.31%,whereas that of the solar cell prepared by conventional method was 14.85%. |
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