Excitation of Wet Perovskite Films by Ultrasonic Vibration Improves the Device Performance

Mohammad-Reza Ahmadian-Yazdi,Mehran Habibi,Morteza Eslamian

doi:10.3390/app8020308

Mohammad-Reza Ahmadian-Yazdi, Mehran Habibi + Show 1 more

Open Access

https://doi.org/10.3390/app8020308

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Journal: Applied sciences	Publication Date: Feb 21, 2018
Citations: 19	License type: CC BY 4.0

Affiliation: Shanghai Jiao Tong University

Abstract

In this work, a novel, facile, and low-cost mechanical post treatment technique, i.e., ultrasonic substrate vibration post treatment (SVPT) is applied on wet spun perovskite layers. The effect of varying the time of the SVPT on the characteristics of the perovskite crystals and the perovskite film is studied, in order to achieve the optimum time duration of the SVPT. Among the results, it is found that the application of only three minutes of the SVPT (for the ultrasonic vibration assembly used in this study, operated at 40 kHz) brings about significant improvement in the film coverage, and the contact between the perovskite and the m-TiO2 layers, owing to the effective penetration of the perovskite solution into the pores, leading to a superior charge transfer, and a significant increase in the device power conversion efficiency (PCE), when compared to the control device. This unprecedented effect is repeatable when applied on both single and mixed halide perovskites, putting forward a reliable and low-cost mechanical technique for the fabrication of perovskite solar cells (PSCs) in the lab and beyond, which could reduce or eliminate the tedious and expensive chemical optimization treatments, commonly used to increase the PCE.

Highlights

Perovskite solar cells (PSCs) are currently one of the most favorable and efficient types of emerging solution-processed thin film solar cells, owing to the excellent optoelectronic properties of the perovskite light harvesters [1,2,3], the device instability under normal operation and the process scale-up, using low-cost fabrication routes, are two major challenges against the commercialization of this technology
Stands for the transparent conducting oxides, such as fluorine-doped tin oxide (FTO), c-TiO2 denotes a compact film of TiO2, m-TiO2 denotes a mesoporous layer made of the TiO2 nanoparticles, and the HTL stands for the hole transporting layer
The c-TiO2 ultrathin layer plays the pivotal role of the electron transporting layer (ETL), whereas the HTL is made of a material that has the ability to transport the holes only, such as spiro-OMeTAD (2,20,7,70 -Tetrakis [N,N-di(4-methoxyphenyl) amino]-9,90 -spirobifluorene)

Summary

Introduction

Perovskite solar cells (PSCs) are currently one of the most favorable and efficient types of emerging solution-processed thin film solar cells, owing to the excellent optoelectronic properties of the perovskite light harvesters [1,2,3], the device instability under normal operation and the process scale-up, using low-cost fabrication routes, are two major challenges against the commercialization of this technology. PSCs may be designed as the p-i-n or n-i-p types, owing to the ambipolar behavior of the perovskite light harvesters. The m-TiO2 layer controls the growth and deposition of the perovskite nanocrystals within the pores of the mesoporous layer, but may be excluded in some designs, so as to simplify the fabrication process and reduce the cost.

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