Roll‐to‐roll gravure printing of organic photovoltaic modules—insulation of processing defects by an interfacial layer

Abstract

Gravure printing as direct patterning roll-to-roll (R2R) production technology can revolutionize the design of thin-film organic photovoltaic (OPV) devices by allowing feasible manufacturing of arbitrary-shaped modules. This makes a distinction to coating methods, such as slot die coating, in which the pattern is limited to continuous stripes. Here, we analyze the thin-film formation and its influence on OPV module performance as the gravure printing of hole transport and photoactive layers are transferred from laboratory to R2R pilot production environment. Insertion of a 0.8-nm layer of lithium fluoride (LiF) as an interfacial layer between the active layer and the electron contact provided insulation against the detrimental pinholes formed in the R2R printing process. Using this device configuration, we produced well-performing R2Rprinted monolithic modules with a mean efficiency of 1.7%. In comparison, reference modules with an efficiency of 2.2% were fabricated using laboratory-scale bench top sheet-level process. Surface energy and tension measurements together with optical microscopy were used to analyze the printability of the materials. The pinhole insulation was investigated in detail by processing R2R-printed OPV modules with different interfacial layer materials and performing electrical measurements under dark and AM1.5 illumination conditions. Furthermore, we analyzed the LiF distribution using X-ray photoelectron spectroscopy. The insulating nature of the LiF layer to improve module performance was confirmed by manufacturing lithographically artificial pinholes in device structures. The results show the possibility to loosen the production environment constraints and the feasibility of fabricating well-performing thin-film devices by R2R gravure printing.

Roll‐to‐Roll Fabrication of Solution Processed Electronics

“…The use of gravure and flexographic printing was also extensively investigated and has demonstrated their promise for the R2R preparation of organic solar cells . These two‐dimensional printing techniques are differentiated from other coating methods by enabling the direct patterning of arbitrarily shaped and sized features, thereby enhancing the freedom to connect the cells in modules.…”

“…R2R pilot production of OPV modules has been realized by researches from VTT . Starting from simple table top equipment, this group was able to transfer lab scale processes to the R2R fabrication of OPV modules using gravure printing and rotary screen printing .…”

Behaviour of one-step spray-coated carbon nanotube supercapacitor in ambient light harvester circuit with printed organic solar cell and electrochromic display

“…The light energy was harvested from office room lighting using a printed organic photovoltaic (OPV) module which was previously reported 35 . The current-voltage (I-V) curves for two OPV modules used in this work are presented in Supplementary Information Fig.…”

New barrier encapsulation and lifetime assessment of printed organic photovoltaic modules

“…A primary advantage of OPV technology is that all of the functional layers in an OPV module can be manufactured by eco-benign, scalable printing or coating technologies [5,6]. Furthermore, the ability to manufacture on flexible plastic substrates using high-speed roll-to-roll manufacturing lines enables significant potential cost benefits for OPV modules compared with other PV technologies [7][8][9][10]. Other features such as the flexibility and light-weight of printed OPV modules are attractive for a variety of diverse applications ranging from power sources for portable electronic devices to building-integrated power-generating PV systems.…”