Gas-solid reaction based over one-micrometer thick stable perovskite films for efficient solar cells and modules

Zonghao Liu,Zhifang Wu,Zafer Hawash,Shengzhong Liu,Sonia R Raga,Emilio J Juarez-Perez,Longbin Qiu,Taehoon Kim,Luis K Ono,Yan Jiang,Yabing Qi

doi:10.1038/s41467-018-06317-8

Abstract

Besides high efficiency, the stability and reproducibility of perovskite solar cells (PSCs) are also key for their commercialization. Herein, we report a simple perovskite formation method to fabricate perovskite films with thickness over 1 μm in ambient condition on the basis of the fast gas−solid reaction of chlorine-incorporated hydrogen lead triiodide and methylamine gas. The resultant thick and smooth chlorine-incorporated perovskite films exhibit full coverage, improved crystallinity, low surface roughness and low thickness variation. The resultant PSCs achieve an average power conversion efficiency of 19.1 ± 0.4% with good reproducibility. Meanwhile, this method enables an active area efficiency of 15.3% for 5 cm × 5 cm solar modules. The un-encapsulated PSCs exhibit an excellent T80 lifetime exceeding 1600 h under continuous operation conditions in dry nitrogen environment.

Highlights

Besides high efficiency, the stability and reproducibility of perovskite solar cells (PSCs) are key for their commercialization
Many solution processable perovskite formation methods have been developed to fabricate high-quality perovskite films, such as onestep method[2,7,8,9] and two-step method[10]. These methods usually involve a transformation of 2D lead halide inorganic framework to the 3D perovskite structure. This structure transformation is often accompanied with the formation of morphological defects and crystallographic structure dislocation within the grain and at grain boundaries, where defects are present as trap states causing serious charge recombination and limiting the charge carrier diffusion length[11,12]
Hydrogen lead triiodide (HPbI3) was used as the starting material aiming at taking advantage of its fully coordinated [PbI3]− structure to reduce iodide-vacancy and improve film quality (Supplementary Figs. 2, 3)[33,34]

Summary

Introduction

The stability and reproducibility of perovskite solar cells (PSCs) are key for their commercialization. Many solution processable perovskite formation methods have been developed to fabricate high-quality perovskite films, such as onestep method[2,7,8,9] and two-step method[10] These methods usually involve a transformation of 2D lead halide inorganic framework to the 3D perovskite structure. A perovskite formation process based on methylamine (CH3NH2) gas−solid reaction has been developed to prepare highquality CH3NH3PbX3 (X = I, Br, Cl), mixed halides CH3NH3+based perovskite and Cesium/CH3NH3+ mixed cations perovskite films[16,17,18] This gas−solid reaction-based method introduces a liquid intermediate, which leads to induced morphology reconstruction, defects healing[19,20]. CH3NH2 gas-based processes are promising for depositing high-quality perovskite films across large area for PSC device fabrication[22,23]

Methods

Results

Conclusion