Surface Passivation Using N-Type Organic Semiconductor by One-Step Method in Two-Dimensional Perovskite Solar Cells

Helong Wang,Fanming Zeng,Xiaoyin Xie,Guanchen Liu,Chongyang Xu,Sheng Wu

doi:10.3390/cryst11080933

Abstract

Surface passivation, which has been intensively studied recently, is essential for the perovskite solar cells (PSCs), due to the intrinsic defects in perovskite crystal. A series of chemical or physical methods have been published for passivating the defects of perovskites, which effectively suppressed the charge recombination and enhanced the photovoltaic performance. In this study, the n-type semiconductor of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is dissolved in chlorobenzene (CB) for the surface passivation during the spin-coating process for depositing the two-dimensional (2D) perovskite film. This approach simplifies the fabrication process of 2D PSCs and benefits the film quality. As a result, the defects of perovskite film are effectively passivated by this method. A better perovskite/PCBM heterojunction is generated, exhibiting an increased film coverage and improved film morphology of PCBM. It is found that this technology results in an improved electron transporting performance as well as suppressed charge recombination for electron transport layer. As a result, PSCs based on the one-step formed perovskite/PCBM heterojunctions exhibit the optimized power conversion efficiency of 15.69% which is about 37% higher than that of regular perovskite devices. The device environmental stability is also enhanced due to the quality improved electron transport layer.

Highlights

Organo-inorganic hybrid perovskite solar cells (PSCs) have grabbed considerable attention due to their excellent characters, such as strong light absorption, long carrier diffusion length, high charge carrier mobility, and cost-effective production [1,2,3,4,5]
Within one decade of development, the power conversion efficiency (PCE) of PSCs has been over 25% [6], reaching a comparable level to those of their commercialized counterparts, e.g., cadmium telluride (CdTe), and copper indium gallium selenide (CIGS) solar cells [7]
We report a facile approach to improve the photovoltaic performance and environmental stability of inverted 2D PSCs by passivating the 2D perovskite with the phenyl-C61-butyric acid methyl ester (PCBM) solution

Summary

Introduction

Organo-inorganic hybrid perovskite solar cells (PSCs) have grabbed considerable attention due to their excellent characters, such as strong light absorption, long carrier diffusion length, high charge carrier mobility, and cost-effective production [1,2,3,4,5]. That is one of the crucial reasons why 2D perovskite devices usually exhibit excellent environmental stability These spacer molecules can effectively suppress the charge transfer when n values are low (i.e., n < 5) [30]. PCE of 12.5% with well suppressed photocurrent hysteresis [29] Their developed 2D PSCs presented obviously enhanced environmental stability compared with the 3D counterparts. Huang’s group obtained the structural order of PCBM layer using the solvent annealing process and the PCE of perovskite sample was improved from 17.1 to 19.4% [33] They argued that the quality improved ETL had a significant impact on the performance of PSCs and the Voc was effectively enhanced. These results provide more aspects about developing the performance of 2D PSCs

Chemicals and Reagents

Device Fabrication

Characterization

Results and Discussion

Conclusions