Performance improvement of perovskite solar cells through enhanced hole extraction: The role of iodide concentration gradient

• Published in: Solar energy materials and solar cells 2018-10, Vol.185, p.117-123
• Main Authors: Wang, Ming, Zang, Zhigang, Yang, Bo, Hu, Xiaofei, Sun, Kuan, Sun, Lidong
• Format: Article
• Language: English
• Subjects: Absorption rates; Additive manufacturing; Circuits; Coatings; Concentration gradient; Energy conversion efficiency; Fabrication; Interfacial modification; Iodide concentration gradient; Iodides; Open circuit voltage; PbI2; Performance enhancement; Perovskite; Perovskite solar cells; Perovskites; Photoluminescence; Photons; Photovoltaic cells; Short circuit currents; Short-circuit current; Solar cells; Solar energy; Spin coating; Tuning
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2018.05.025

Realization of fast hole extraction is an effective route for the performance enhancement of inverted perovskite solar cells (PSCs). The precise bandgap tuning in perovskite layer has been expected to accelerate hole extraction. Therefore, in this report, we demonstrate a modified one-step fabrication method for the bandgap tuning of perovskite layer by designing iodide concentration gradient. Prior to the perovskite precursor solution spin-coated, different concentration of methanaminium iodide (MAI) solution was pre-coated on PEDOT:PSS layer to form iodide concentration gradient in perovskite layer. Fast hole extraction and short lifetime due to iodide concentration gradient was confirmed by photoluminescence measurement. By optimizing the MAI concentration with 4 mg/ml, the modified PSCs exhibited a power conversion efficiency of 16.67% due to an increase in short-circuit current density (Jsc) from 19.66 mA/cm2 to 23.52 mA/cm2 and an increase in open circuit voltage from 0.97 V to 1.01 V. These values are significantly higher than PSCs using conventional one-step fabrication method without pre-coated MAI layer, which exhibit efficiency of only 14.8%. We think that this new approach is an effective way to enhance the performance of PSCs. [Display omitted] •A modified one-step spin coating method for perovskite solar cells fabrication was proposed.•An appropriate amount of methanaminium iodide (MAI) was spin-coated on PEDOT:PSS layer to form iodide concentration gradient in perovskite layer.•Fast hole extraction and short lifetime due to iodide concentration gradient was confirmed.