The impact of synthesis techniques on the properties of hybrid perovskite materials for photovoltaic application

Abstract

Hybrid perovskites are organometal halide materials that are attractive to the researchers owing to impressive physical properties like absorption coefficients. Controlled formation of perovskite crystal during the preparation process is key to achieving better morphological features, thereby influencing the material's properties. In this paper, we examined the impact of two synthesis techniques as well as new material composition on the properties of the perovskite materials. These perovskite materials were produced by one- and two-step solution processes and the kinetics of the composition of perovskite were characterized by the following techniques: UV-vis spectroscopy, X-ray diffraction (XRD) and Thermo gravimetric analysis. The electrochemical properties were examined by cyclic voltammetry using the two-electrode system. All samples exhibited an absorption onset around 850 nm which corresponded well with the energy gap (∼1.55 eV). The two-step process resulted in smooth XRD patterns, hence exhibiting improved crystallinity owing to sharper peaks than those from one-step process. The sample crystallite sizes ranged of 44–81 nm. We conclude that two synthesis techniques together with new materials composition showed better thermal stability compared with previous reports. Cyclic voltammetry indicated that the perovskite electrodes exhibited stable electrochemical performance and easy charge transfer during the reaction. Our results suggest better electrochemical properties with possible capacitance which is beneficial for energy storage devices.

Hybrid Perovskite Thin Film

“…From our work [8,11], the annealing temperature had strong impact on the formation of perovskite. The under-and over-annealing were both detrimental to cell performance.…”

“…Any deviation from stoichiometric ratio (PbCl 2 : MAI) can lead to either excessive MAI or unreacted PbCl 2 to remain inside the film, which can be expected to decompose their resulting optoelectronic performance. For example, the MAI and PbI 2 (1: 1 mole ratio) and the mixture of PbCl 2 and MAI solution, a nonstoichiometric mole ratio of 5: 3 is demonstrated to be optimum for the formation of perovskite precursor [8]. It should be noted that the mixed halide shows enhanced film properties, for instance.…”

“…The molar ratios of 1:1and 1:3 have been the most commonly used for perovskite precursors. But other molar ratios which are non-stoichiometric are reported in [7,8].…”