Characteristics of sputtered ZnO films for buffer layer in inverted organic solar cells

• Published in: Thin solid films Vol. 547; pp. 3 - 8
• Main Authors: Lee, Jae-Hyeong, Hong, Byungyou, Park, Yong Seob
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 29.11.2013; Elsevier
• Subjects: Applied sciences; Buffer layers; Cell efficiency; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallinity; Density; Deposition by sputtering; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Energy; Exact sciences and technology; Grain size; Inverted organic solar cell; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Photovoltaic cells; Photovoltaic conversion; Physics; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Solar power generation; Sputtering; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Unbalanced magnetron sputtering; Zinc oxide; ZnO; Cell efficiency; Inverted organic solar cell; ZnO; Crystallinity; Unbalanced magnetron sputtering; Solar cells; Buffer layer; Grain size; Electrical conductivity; Oxide layer; Surface morphology; Under bump metallization; Sputtering; Thin films; Cathode sputtering; Optical properties; Physical vapor deposition; Zinc oxide; Sputter deposition; Carrier mobility
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.06.045

In this work, we describe the characterizations of zinc oxide (ZnO) buffer layers deposited by unbalanced magnetron (UBM) sputtering under various target power densities for inverted organic solar cells (IOSCs). UBM sputter grown ZnO buffer layers exhibited higher crystallinity with increases in target power density, resulting in large grain size, uniform surface morphology, and low resistivity. In addition, it was found that the performance of IOSCs critically depended on the target power density for sputtering of the ZnO buffer layer because the crystalllinity of the ZnO buffer layer affect the carrier mobility of the ZnO buffer layer. For this reason, the IOSC with ZnO buffer layer sputtered at higher target power density showed the better cell performance. Furthermore, we correlated the improved efficiency of the IOSC with the electrical, optical, and structural properties of the UBM sputter grown ZnO buffer layer to design more efficient IOSC with ZnO buffer layer. •Fabrication of zinc oxide films by unbalanced magnetron sputtering.•Effects of target power density on zinc oxide properties.•Fabrication of inverted organic solar cells using ZnO film as the buffer layer.•The maximum power conversion efficiency about 1.99%.