Influence of the Porosity of the TiO2 Film on the Performance of the Perovskite Solar Cell

Xiaodan Sun,Jia Xu,Jing Chen,Li Xiao,Bing Zhang,Jianxi Yao,Songyuan Dai

doi:10.1155/2017/4935265

Abstract

The structure of mesoporous TiO2 (mp-TiO2) films is crucial to the performance of mesoporous perovskite solar cells (PSCs). In this study, we fabricated highly porous mp-TiO2 films by doping polystyrene (PS) spheres in TiO2 paste. The composition of the perovskite films was effectively improved by modifying the mass fraction of the PS spheres in the TiO2 paste. Due to the high porosity of the mp-TiO2 film, PbI2 and CH3NH3I could sufficiently infiltrate into the network of the mp-TiO2 film, which ensured a more complete transformation to CH3NH3PbI3. The surface morphology of the mp-TiO2 film and the photoelectric performance of the perovskite solar cells were investigated. The results showed that an increase in the porosity of the mp-TiO2 film resulted in an improvement in the performance of the PSCs. The best device with the optimized mass fraction of 1.0 wt% PS in TiO2 paste exhibited an efficiency of 12.69%, which is 25% higher than the efficiency of the PSCs without PS spheres.

Highlights

Perovskite solar cells based on CH3NH3PbI3 have attracted much attention
For a low mass fraction of 0.5 wt% PS spheres in the paste (PS-0.5), a few pores with an average size of 70 nm are formed on the surface of the mesoporous TiO2 (mp-TiO2) layer
As the mass fraction of PS spheres increases to 1.5 wt% (PS-1.5), pores with relative larger pores (94 nm) were formed due to the high mass fraction of PS spheres and the agglomeration of PS spheres in the TiO2 paste

Summary

Introduction

Perovskite solar cells based on CH3NH3PbI3 have attracted much attention. Tremendous progress has been made since the seminal work of Kojima et al in 2009 [1]. Power conversion efficiencies (PCEs) of PSCs have increased sharply from 3.8% [1] to 22.1% [2], which exceeds the PCEs of polycrystalline silicon solar cells [3,4,5]. Their solution processability and low cost endow them with high potential for generation solar cells [4, 6]. Two typical PSC structures are widely used, including the planar heterojunction architectures [7] and the mesoporous structures [8,9,10]. The mp-TiO2 film acts as the scaffold of the perovskite layer and as the pathway for electron transport [14]

Methods

Results

Conclusion