Recent progress of transparent conductive electrodes in the construction of efficient flexible organic solar cells

Abstract

Flexible transparent conducting electrodes (F-TCEs) are an important part of a flexible solar cell. The performance of the F-TCEs is very important for the transmission of light and charge. Therefore, the selection of appropriate characteristics of F-TCES, especially electrical conductivity, light transmittance, and mechanical flexibility, is essential for fabricating solar cells with high performance. This article reviewed the latest development of F-TCEs and the structural design of flexible solar cells, compared and analyzed the preparation methods, advantages, and disadvantages of several different F-TCEs, such as metal oxides, metals, carbon materials, polymers, and their composites. Based on different solar cell structures and flexible substrate types, the measures to obtain high transmittance, low resistance, etc., were emphatically discussed to obtain F-TCEs with excellent performance. In order to make up for the shortcomings of single electrode materials, the current development of composite F-TCEs electrodes was discussed and analyzed. Finally, the challenges faced by F-TCEs and future development direction were prospected, providing a reference for the design of future intelligent photovoltaic systems.

A review on polymers and their composites for flexible electronics

“…The flexible plastic film used for the flexible display exhibits reasonable trade-offs in mechanical, optical, and chemical properties, which can be produced by a roll-to-roll process and adapt to high-temperature processing technology. [75][76][77] Nevertheless, compared with inorganic glass, common plastic substrate materials have inferior transparency, high thermal expansion coefficient (CTE), 78 permeability to water and oxygen, and easily deformed, which affect the service life of the display, and thus it is necessary to design the molecular structure to improve performance of the polymers and ameliorate technological processes to overcome the existing problems for meeting the increasing demands in society.…”

Recent advances in nanofiber-based flexible transparent electrodes

“…This FTE demonstrates excellent tensile strength and flexibility, the fracture strain can reach 70%, and the efficiency of the device remains above 85% when the bending radius is 3 mm. Compared with materials such as metal thin films, metal nanowires and conductive grids [285,286], it has a higher light transmittance and mechanical flexibility while ensuring excellent energy conversion efficiency. Kang et al prepared organic solar cells with ordered networks of metal NFs using simple transfer printing, and achieved a power conversion efficiency superior to that of traditional ITO electrodes [287].…”

Sequentially Coated Wavy Nanowire Composite Transparent Electrode for Stretchable Solar Cells

“…Furthermore, as the next form factor, stretchable or deformable optoelectronic devices have been actively studied in recent years. − For stretchable and deformable optoelectronic devices, it is essential to secure the stretchability of the transparent electrode transmitting the lights and transporting the electrons. In the current flexible devices, flexible transparent electrodes are manufactured by thinly coating a rigid transparent electrode material such as indium tin oxide (ITO) on ultrathin glass or colorless polyimide flexible substrates. − However, since it is highly challenging to stretch a nonstretchable transparent electrode material structurally, a stretchable transparent electrode (STE) material needs to be newly developed.…”