Di Gu

High-performance perovskite CH3NH3PbI3 thin films for solar cells prepared by single-source physical vapour deposition

In this work, an alternative route to fabricating high-quality CH3NH3PbI3 thin films is proposed. Single-source physical vapour deposition (SSPVD) without a post-heat-treating process was used to prepare CH3NH3PbI3 thin films at room temperature. This new process enabled complete surface coverage and moisture stability in a non-vacuum solution. Moreover, the challenges of simultaneously controlling evaporation processes of the organic and inorganic sources via dual-source vapour evaporation and the heating process required to obtain high crystallization were avoided. Excellent composition with stoichiometry transferred from the powder material, a high level of tetragonal phase-purity, full surface coverage, well-defined grain structure, high crystallization and reproducibility were obtained. A PCE of approximately 10.90% was obtained with a device based on SSPVD CH3NH3PbI3. These initial results suggest that SSPVD is a promising method to significantly optimize perovskite CH3NH3PbI3 solar cell efficiency.

Doped tin induced structural evaluation and performance of CH3NH3PbxSn1-xI3 thin films prepared by a simple route of unisource thermal evaporation

The photoelectric conversion efficiency of organic–inorganic halide perovskite solar cell has made a great progress in recent years. In this paper, we attempted to gradually replace lead with tin and synthesize perovskite thin films of different lead–tin proportion with a unisource thermal evaporation method. The morphology, crystallinity and transmittance of the perovskite thin films were studied for revealing the effect of different lead and tin proportion on the properties of the perovskite thin films. The results show that the morphology was ameliorated and the crystallinity of CH3NH3Pb0.4Sn0.6I3 thin film was improved. The absorption edge of CH3NH3Pb0.7Sn0.3I3 was moved to the long wavelength. The surface of the perovskite thin films was smoother and the quality of the thin films has been greatly improved.

Enhanced Crystallinity and Performance of CH3NH3PbI3 Thin Film Prepared by Controlling Hot CH3NH3I Solution Onto Evaporated PbI2 Nanocrystal

In this paper, a facile, efficient, and reduplicative modified two-step sequential method for the fabrication of CH ₃NH₃PbI₃ thin film was reported. First, a uniform, homogeneous, and small-sized PbI₂ nanocrystal was deposited via vapor evaporation. Then, a hot CH₃NH₃I solution with a different temperature was spin coated onto the prepared PbI₂ thin film to form perovskite thin films in a short time. The results demonstrated that homogeneous, compact, complete surface coverage, high crystallinity, and pinhole-free CH₃NH₃PbI₃ thin film was prepared by CH₃NH₃I solution with 80°C spin coating on the evaporated PbI₂ nanocrystal.

Synthesis and Characterization of CH3NH3Pb1-xSnxI3 Crystal

The CH3NH3PbI3 light-absorbing layer shows preferably photovoltaic performance. However, comparing with CH3NH3PbI3 film, the CH3NH3SnI3 film show smaller band gap and wider light absorption range, meanwhile, it is non-toxic and environmental friendly solar cell material. In this paper, different proportions of tin (Sn) was doped into CH3NH3PbI3 film, the atomic ratio of lead-tin strictly controlled to form CH3NH3SnI3 from CH3NH3PbI3. The five different proportions of doping CH3NH3Pb1-xSnxI3 perovskite powders were studied. The morphology of powders was observed by scanning electron microscopy (SEM). X-ray diffraction (XRD) and energy dispersive spectrum (EDS) were used to analyze the crystallization and the proportion composition of powders, respectively. The experimental results show that the powder crystal orientation was very obvious at the ratio of lead-tin around 1:1.99 and the atomic ratio close to the ideal stoichiometric ratio of doped atoms.