A two-step dry process for Cs₂SnI₆ perovskite thin film

Abstract

A two-step process for synthesizing stable Cs 2 SnI 6 perovskite thin films is reported in this letter. The two-step process includes the co-evaporation of two precursors SnI 2 and CsI onto a glass substrate, followed by a post thermal annealing process in iodine vapor. Using this technique, pure Cs 2 SnI 6 perovskite thin films were successfully synthesized without any wet process. These perovskite thin films are found to be stable under ambient conditions. They also show an electron mobility up to 509 cm 2 V −1 s −1 , which is higher than the mobilities of films prepared by solution processes reported in the literature. IMPACT STATEMENTA novel two-step dry process to synthesize phase-pure, air-stable Cs 2 SnI 6 perovskite thin film with higher electron mobility than that of the films prepared by the solution process.

Fabrication and characterization of lead‐free Cs 2 SnI 6 perovskite films for photovoltaic applications

“…Here, the calculated bandgap values for the SnI 4 prepared film is smaller than the reported values of 1.58 eV for the Cs 2 SnI 6 film prepared by evaporating and annealing CsI in SnI 4 vapor 34 . The calculated bandgap of the films confirms the direct bandgap nature of the Cs 2 SnI 6 as suggested in several reports 33‐34 Figure S2. shows the transmission percentage spectra of the SnI 2 and I 2 films at 210°C and 225°C.…”

“…34 The calculated bandgap of the films confirms the direct bandgap nature of the Cs 2 SnI 6 as suggested in several reports. [33][34] Figure S2 shows the transmission percentage spectra of the SnI 2 and I 2 films at 210 C and 225 C. The films showed a sharp increase in transmission near 820 nm wavelength. Figure 9 shows the photolumnicesnce spectra of the prepared films at210 C in the wavelength range of 600-1050 nm with an excitation wavelength of 633 nm.…”

“…The structure of the Cs 2 SnX 6 is a defect variant of the perovskite having nominal composition of ABX 3 , where half of the B‐sites are vacant, which results in the formation of isolated [SnX6] octahedra. Cs‐atoms occupy the sites between the [SnX6] octahedra in a regular 12‐fold coordination environment of X atoms 27‐34 …”

“…Until the present date, little success has been achieved in fabricating efficient Cs 2 SnI 6 PSCs as the PCE is still relatively low (~1%). Several researchers have reported different fabrication techniques and processing conditions to further optimize the properties of Cs 2 SnI 6 perovskite 30‐36 . Guo et al 33 prepared the Cs 2 SnI 6 films via vacuum co‐evaporation using CsI and SnI 2 precursors and suggested that using SnI 4 may not form continuous film because it is vulnerable to thermal decomposition on heating.…”

Optical Characterization of Lead-Free Cs2SnI6 Double Perovskite Fabricated from Degraded and Reconstructed CsSnI3 Films

“…30 Several synthesis methods have been employed for its preparation. 25,31,32 However, the optical properties of this material have not been broadly studied in the literature. In this work, the optical properties of the Cs 2 SnI 6 , obtained as final degradation product of the CsSnI 3 in air, are studied in depth.…”