Solvent and Spinning Speed Effects on CH₃NH₃PbI₃ Films Deposited by Spin Coating

Abstract

Herein, methylammonium lead triode (CH 3 NH 3 PbI 3 ) perovskite thin films are prepared by the one-step deposition spin-coating process on glass substrates. The effects of solvent nature and speed centrifugation on films' morphology and structure are investigated. Two solvents are used: N,N-dimethyl formamide (DMF) and a mixture of dimethyl sulfoxide (DMSO) with DMF. The spinning speed varies in the range 700-2000 rpm. Scanning electron microscopy (SEM) observations reveal that the prepared films are not continuous with variable morphologies; the films are formed with elongated fibers. X-ray diffraction (XRD) analysis confirms the tetragonal structure of the prepared perovskite. The film structure is also investigated by Raman spectroscopy. The film's optical properties are studied using UV spectroscopy. The results indicate that solvent nature and spinning velocity alter film morphology. With increasing spinning velocity, the films' porosity increases. The films' formation is controlled by the competition between the radial force due to spinning velocity and resistive force due to solution viscosity.

Realization and Characterization of CH₃NH₃PbI₃ /c-Si Heterojunction

“…Based on Williamson-Hall method [15,22] described by Eq. 1, the average crystallites size and the deformation in the peronskite film were evaluated.…”

“…The perovskite film was deposited on cleaned (P) c-Si substrate by spin-coating technique at ambient air using a CH3NH3PbI3 solution prepared with equimolar of PbI2 and CH3NH3I in mixture solvent of N,N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). This solvent was used since it provides films with less porosity according to a previous work [15]. The centrifugation speed was fixed at 1500 rpm for 40 s to assure a better coating of the substrate surface.…”

“…The centrifugation speed was fixed at 1500 rpm for 40 s to assure a better coating of the substrate surface. More details are available in our previous study [15].…”

“…Finaly, the metal contacts were formed by depositing an Au thin film on both heterojunction sides by DC sputtering. The film surface morphology was investigated using a Horiba Scientific JSM-7100 scanning electron microscope however the film structural and optical properties were defined by analysing a CH3NH3PbI3 film deposited in the same conditions on glass substrate [15]. The heterojunction characterization was made by I-V and G-f measurements using 370 programmable curve tracer and Agilent 4284A LCR-meter respectively.…”

Influence of chemical conversion parameters and resulting PbI2 content on carrier density and morphology of the p-type electrodeposited hybrid perovskite CH3NH3PbI3

“…Among scalable deposition methods, spin coating is the most common, useful and inexpensive method for the fabrication of perovskite solar cell devices [5,21,22]. However, this method is only suitable for J o u r n a l P r e -p r o o f small area deposition on flat substrates and it produces undesirable highly rough and porous surfaces [23], which limits its commercial use. Several other scalable deposition methods were also employed such as atomic layer deposition (ALD) [24], spray deposition (SD) [25], and doctor blade technique (DB) [26].…”