ZnO:Ga-graded ITO electrodes to control interface between PCBM and ITO in planar perovskite solar cells

Hae-Jun Seok; Azmat Ali; Jung Hwa Seo; Hyun Hwi Lee; Na-Eun Jung; Yeonjin Yi; Han-Ki Kim

doi:10.1080/14686996.2019.1599695

ZnO:Ga-graded ITO electrodes to control interface between PCBM and ITO in planar perovskite solar cells

Sci Technol Adv Mater. 2019 Apr 25;20(1):389-400. doi: 10.1080/14686996.2019.1599695. eCollection 2019.

Authors

Hae-Jun Seok¹, Azmat Ali², Jung Hwa Seo², Hyun Hwi Lee³, Na-Eun Jung⁴, Yeonjin Yi⁴, Han-Ki Kim¹

Affiliations

¹ School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
² Department of Materials Physics, Dong-A University, Busan, Republic of Korea.
³ Pohang Accelerator Laboratory, POSTECH, Pohang, Republic of Korea.
⁴ Institute of Physics and Applied Physics, Yonsei University, Seoul, Republic of Korea.

Abstract

Ga-doped ZnO (GZO)-graded layer, facilitating electron extraction from electron transport layer, was integrated on the surface of transparent indium tin oxide (ITO) cathode by using graded sputtering technique to improve the performance of planar n-i-p perovskite solar cells (PSCs). The thickness of graded GZO layer was controlled to optimize GZO-indium tin oxide (ITO) combined electrode for planar n-i-p PSCs. At optimized graded thickness of 15 nm, the GZO-ITO combined electrode showed an optical transmittance of 95%, a resistivity of 2.3 × 10^-4 Ohm cm, a sheet resistance of 15.6 Ohm/square, and work function of 4.23 eV, which is well matched with the 4.0-eV lowest unoccupied molecular orbital of [6,6]-phenyl-C₆₁-butyric acid methyl ester. Owing to enhanced extraction of electron by the graded GZO, the n-i-p PSC with GZO-ITO combined electrode showed higher power conversion efficiency (PCE) of 9.67% than the PCE (5.25%) of PSC with only ITO electrode without GZO-graded layer. In addition, the GZO integrated-ITO electrode acts as transparent electrode and electron extraction layer simultaneously due to graded mixing of the GZO at the surface region of ITO electrode.

Keywords: 107 Glass and ceramic materials; 201 Electronics / Semiconductor / TCOs; 209 Solar cell / Photovoltaics; 306 Thin film / Coatings; 50 Energy Materials; Ga-doped ZnO; ITO; electron extraction layer (EEL); graded sputtering; perovskite solar cells.

Grants and funding

This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea: [Grant Number 20163010012200] and the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP): [Grant Number 2018R1A2B2003826]. This study also received partial support from Korea Electric Power Corporation (KEPCO) [Grant Number : CX72170049].