Overview of printing and coating techniques in the production of organic photovoltaic cells

Abstract

The organic photovoltaic cell (OPV) is composed of multiple layers, and some printing and coating techniques are more suitable than others for a certain type of layer. This paper aims to characterize and compare the most relevant coating and printing techniques that can be used in the manufacture of OPVs. Extensive bibliographic research was carried out on articles published from 1998 to 2020 to identify various aspects OPV, such as the principle of operation, advantages, disadvantages, and which layers can be printed by each technique. The results show that the most used method for the processing of OPVs is spin-coating. In the studies found, rotation was used to coat the active layer, the electron transport layer, and the hole transport layer. The techniques of pad printing, casting, and meniscus are considered useful in the processing of the active layer. Regarding the deposition of the active layer, hole transport layer, electron transport layer, and anode, the rotogravure, crack matrix, spraying, and brushing techniques were satisfactory. Flexography has been used to form the active layer, electron transport layer, and anode. Screen printing, inkjet printing, and knife/blade coating were used in the processing of the active layer, hole transport layer, electron transport layer, anode, and cathode. All the double slot die coating, curtain coating, and slide coating allows simultaneous processing of multiple layers. Techniques compatible with roll-to-roll processing are more likely to be at the center of OPVs in the future, thus making solar photovoltaic technology more competitive.

Indoor Perovskite Photovoltaics for the Internet of Things—Challenges and Opportunities toward Market Uptake

“…The majority of fabrication methods and corresponding processing conditions are common for both indoor and AM1.5G illuminated PPV and OPV devices. Discussions on upscaling techniques have already been extensively reported by several noteworthy literature reviews [ 121–129 ] focusing on similar perovskite devices that are exposed to AM1.5G illumination. These processes are divided into wet‐ and vacuum processing techniques.…”

“…Screen printing is an easy and popular technique that allows the development of precisely patterned films. Its low cost of fabricating the whole layer stack of a PPV cell or module, however, is contradicted with its incompatibility as a technique to handle less viscous fluids, since inks with lower viscosities will pass straight through the screen openings [ 129 ] and will result to inhomogeneous films that will most probably follow the pattern of the mesh. Developing both homogeneous and thin films would be highly expensive due to the need for ultra‐high resolution meshes and tailor‐cut material rheologies, or most probably impossible.…”

“…Its use is mainly restricted to certain architectures and materials that have higher viscosities, mostly pastes. Resulting layer thicknesses are usually in the range of microns (10–500 µm) [ 129 ] and up to few decades of microns for PPV modules. [ 145,146 ]…”

“…The R2R‐compatible version of it, which is called rotary‐screen printing, can yield kilometers of precisely patterned films with negligible material wastage. [ 129 ] However, the S2S‐compatible version, flat‐bed screen printing, is appropriate for batch production and can as well be used for large‐area and large‐scale fabrication purposes. After deposition, the remaining paste can be reused in case material purity is not compromised.…”

Breakup Dynamics of Thin Liquid Sheets With Viscous Interfaces

“…Industrial applications such as aerosol droplet generation [20], inkjet printing [21] and monodisperse emulsions fabrication [22] rely on the rupture of thin liquid sheets in their procedure. However, the breakup process of thin films can be undesirable in applications such as slot die and curtain coating [23]. Figure 1.3 (adapted from [24,25]) portrays an atomization procedure on the left and a curtain coating process on the right.…”