The introduction of excess PbI2 into CH3NH3PbI3 precursors has been reported to boost the efficiency of CH3NH3PbI3 solar cell. It was assumed that the excess PbI2 helped to reduce the defect density in CH3NH3PbI3 solar cell. In this work, by adding non-equimolar PbI2 into CH3NH3PbI3 precursor solution, PbI2-rich CH3NH3PbI3 solar cells have been fabricated. The efficiency of CH3NH3PbI3 solar cell was significantly improved from 14.14% to 16.80%. Results obtained from scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate that the excess PbI2 does not affect the morphological and crystal properties of CH3NH3PbI3 thin film. Based on time-resolved photoluminescence (TRPL) measurement, it was found that the carrier lifetime of PbI2-rich perovskite thin film was significantly increased. Lower defect density was observed in PbI2-rich CH3NH3PbI3 solar cell by admittance spectroscopy (AS) characterization, indicating PbI2 can suppress the formation of defects in CH3NH3PbI3 solar cells.

/pdf/observation-of-lower-defect-density-brought-by-excess-pbi2-2iyj3mex48.pdf

Observation of lower defect density brought by excess PbI2 in CH3NH3PbI3 solar cells

Growth kinetics of hybrid perovskite thin films on different substrates at elevated temperature and its direct correlation with the microstructure and optical properties

Kinetic Monte Carlo simulations of a model of thin film heteroepitaxy are performed to investigate the effects of the deposition temperature in the initial growth stages. Broad ranges of the rates of surface processes are used to model materials with several activation energies and several temperature changes, in conditions of larger diffusivity on the substrate in comparison with other film layers. When films with the same coverage are compared, the roughness increases with the deposition temperature in the regimes of island growth, coalescence, and initial formation of the continuous films. Concomitantly, the position of the minimum of the autocorrelation function is displaced to larger sizes. These apparently universal trends are consequences of the formation of wider and taller islands, and are observed with or without Ehrlich-Schwöebel barriers for adatom diffusion at step edges. The roughness increase with temperature qualitatively matches the observations of recent works on the deposition of inorganic and organic materials. In thicker films, simulations with some parameter sets show the decrease of roughness with temperature. In these cases, a re-entrance of roughness may be observed in the initial formation of the continuous films.

/pdf/temperature-effects-in-the-initial-stages-of-heteroepitaxial-1lpg5ge2.pdf

Temperature Effects in the Initial Stages of Heteroepitaxial Film Growth

Structural and Optical Properties of Two-Step Dip-Coated CH3NH3PbI3 Films Based on Underlying Dip-Coated PbI2 Films

The invention discloses a high-quality LED manufacturing method which comprises the following steps of S1) silicon chip inspection; S2) silicon chip cleaning; S3) silicon chip polishing; S4) diffusion; S5) thermal oxidation; S6) photo-etching; S7) alloy sintering; S8) vacuum film coating; S9) angle making in the inclined side; S10) welding; S11) pickling; S12) solidification of white glue; S13) moulding; and S14) post treatment. The method is reasonable in design, a selective diffusion area is etched in a silicon dioxide layer of a silicon chip by thermal oxidation, impurities can be diffusedto the silicon chip in the area, a pneumatic (non-contact) measuring instrument is used for measurement to avoid damage on the surface of the silicon chip, and improve the quality of the raw materialsilicon chip fundamentally, and via silica mechanical polishing, SiO2 colloid generates mechanical friction on the silicon chip, and polishing is used to remove the surface damage layer.

High-quality LED (light emitting diode) manufacturing method

The growth dynamics of CH3NH3PbI3 (MAPbI3) perovskite thin films, deposited by thermal evaporation, has been investigated by atomic force microscope and height–height correlation function analysis. The unstable scaling behavior of initial perovskite films exhibiting the growth of islands, resulting in rougher film formation has been observed. After the formation of continuous film, the roughening has been characterized by analyzing the scaling exponent α ~ 0.70, growth exponent β = 0.79 ± 0.057, 1/z = 0.78 ± 0.038, and 2D fast Fourier transform. Anomalous scaling behavior of the MAPbI3 thin films and the formation of the rapid surface roughening are discovered. It is demonstrated that step-edge barrier induced mound growth may play the dominate role in the growth mechanism of MAPbI3 thin films on Si substrates. Further, the growth behavior of MAPbI3 film on ITO substrates is investigated as a comparison, and it reveals that the growth of MAPbI3 thin films is largely affected by the initial substrates underneath the growing films.

https://iopscience.iop.org/article/10.1088/2053-1591/aa7971/pdf

Scaling behavior and morphology evolution of CH3NH3PbI3 perovskite thin films grown by thermal evaporation

The invention discloses a manufacturing method of a diode and the diode fabricated by the manufacturing method. The manufacturing method comprises the steps of diode grain crystal fabrication, filling, welding, cleaning and package. Due to different thermal expansion coefficients and deformation of a grain crystal and a welding sheet, the grain crystal can be automatically stretched after weldingwithout grain crystal alignment in advance before welding, the pore area is greatly reduced, and the welding quality is improved. A mixed acid prepared from hydrofluoric acid, acetic acid, sulfuric acid and nitric acid according to a volume ratio being 8.8:13:5.6:9.2 is high in grain crystal electrical conductivity after pickling.

Manufacturing method of diode and diode fabricated by manufacturing method

The invention discloses a mixed acid for cleaning a diode, a production method of the mixed acid and a diode cleaning method. The mixed acid for cleaning the diode comprises hydrofluoric acid, aceticacid, sulfuric acid and nitric acid, wherein the volume ratio of the hydrofluoric acid, the acetic acid, the sulfuric acid and the nitric acid is 8.8:13:5.6:9.2. The production method of the mixed acid comprises the steps of adding the acetic acid with concentration being 99.6-99.9% into a container at a temperature 25+/-5 DEG C, adding the hydrofluoric acid with concentrating being 49+/-0.05%, stirring for 10-15 minutes, adding the nitric acid with concentration being 68+/-0.5%, stirring for 15 minutes, finally adding the sulfuric acid with concentrating being 98.1+/-0.5%, and stirring for 2-3 hours after mixing. An ammonia water formula is intruded to a final washing process of pickling, and the problem that substances such as copper and lead are difficult to wash is solved. By the mixedacid and the production method thereof, high-performance pickling can be achieved, the electricity yield and the product quality are further improved by improving picking yield of a pn junction, tworeliable indexes of high-temperature reverse bias and high-temperature storage of a diode are effectively improved, and the product has more competitive advantage.

Mixed acid for cleaning diode, production method of mixed acid and diode cleaning method

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Scaling behavior and morphology evolution of CH3NH3PbI3 perovskite thin films grown by thermal evaporation

Manufacturing method of diode and diode fabricated by manufacturing method

Mixed acid for cleaning diode, production method of mixed acid and diode cleaning method