Custom-Shaped Organic Photovoltaic Modules-Freedom of Design by Printing

Printing and Coating Techniques for Scalable Organic Photovoltaic Fabrication

Within recent years, there has been an increased interest towards organic photovoltaics (OPVs), especially with their significant device performance reaching beyond 19% since 2022. With these advances in the device performance of laboratory-scaled OPVs, there has also been more attention directed towards using printing and coating methods that are compatible with large-scale fabrication. Though large-area (>100 cm2) OPVs have reached an efficiency of 15%, this is still behind that of laboratory-scale OPVs. There also needs to be more focus on determining strategies for improving the lifetime of OPVs that are suitable for scalable manufacturing, as well as methods for reducing material and manufacturing costs. In this paper, we compare several printing and coating methods that are employed to fabricate OPVs, with the main focus towards the deposition of the active layer. This includes a comparison of performances at laboratory (<1 cm2), small (1-10 cm2), medium (10-100 cm2), and large (>100 cm2) active area fabrications, encompassing devices that use scalable printing and coating methods for only the active layer, as well as "fully printed/coated" devices. The article also compares the research focus of each of the printing and coating techniques and predicts the general direction that scalable and large-scale OPVs will head towards.

A Thermoelectric Polymer Field-Effect Transistor via Iodine-Doped P3HT

Doping can alter certain electronics, including the thermoelectric properties of an organic semiconductor. These alterations may enable viable tunable devices that could be useful in temperature sensing for autonomous controls. Here, we demonstrate a dual-modulation organic field-effect transistor (OFET) where temperature can modulate the current-voltage characteristics of the OFET and gate voltage can modulate the thermoelectric properties of the active layer in the same device. Specifically, Poly(3-hexylthiophene-2,5-diyl) (P3HT) was utilized as the host p-type semiconducting polymer, and iodine was utilized as the thermoelectric minority dopant. The finished devices were characterized with a semiconductor analyzer system with temperature controlled using two thermoelectric cooling plates. The FETs with iodine doping levels in the range of 0.25% to 0.5% mole ratio with respect to the P3HT exhibit the greatest on/off ratios. This study also observed that P3HT thin film samples with an intermediate iodine doping concentration of 0.25% mole ratio exhibit an optimal thermoelectric power factor (PF).

Printing fabrication of large-area non-fullerene organic solar cells

Organic solar cells (OSCs) based on a bulk heterojunction structure exhibit inherent advantages, such as low cost, light weight, mechanical flexibility, and easy processing, and they are emerging as a potential renewable energy technology. However, most studies are focused on lab-scale, small-area (<1 cm²) devices. Large-area (>1 cm²) OSCs still exhibit considerable efficiency loss during upscaling from small-area to large-area, which is a big challenge. In recent years, along with the rapid development of high-performance non-fullerene acceptors, many researchers have focused on developing large-area non-fullerene-based devices and modules. There are three essential issues in upscaling OSCs from small-area to large-area: fabrication technology, equipment development, and device component processing strategy. In this review, the challenges and solutions in fabricating high-performance large-area OSCs are discussed in terms of the abovementioned three aspects. In addition, the recent progress of large-area OSCs based on non-fullerene electron acceptors is summarized.

Manipulating nanoscale structure to control functionality in printed organic photovoltaic, transistor and bioelectronic devices

Printed electronics is simultaneously one of the most intensely studied emerging research areas in science and technology and one of the fastest growing commercial markets in the world today. For the past decade the potential for organic electronic (OE) materials to revolutionize this printed electronics space has been widely promoted. Such conviction in the potential of these carbon-based semiconducting materials arises from their ability to be dissolved in solution, and thus the exciting possibility of simply printing a range of multifunctional devices onto flexible substrates at high speeds for very low cost using standard roll-to-roll printing techniques. However, the transition from promising laboratory innovations to large scale prototypes requires precise control of nanoscale material and device structure across large areas during printing fabrication. Maintaining this nanoscale material control during printing presents a significant new challenge that demands the coupling of OE materials and devices with clever nanoscience fabrication approaches that are adapted to the limited thermodynamic levers available. In this review we present an update on the strategies and capabilities that are required in order to manipulate the nanoscale structure of large area printed organic photovoltaic (OPV), transistor and bioelectronics devices in order to control their device functionality. This discussion covers a range of efforts to manipulate the electroactive ink materials and their nanostructured assembly into devices, and also device processing strategies to tune the nanoscale material properties and assembly routes through printing fabrication. The review finishes by highlighting progress in printed OE devices that provide a feedback loop between laboratory nanoscience innovations and their feasibility in adapting to large scale printing fabrication. The ability to control material properties on the nanoscale whilst simultaneously printing functional devices on the square metre scale is prompting innovative developments in the targeted nanoscience required for OPV, transistor and biofunctional devices.

Gravure-Printed Flexible Perovskite Solar Cells: Toward Roll-to-Roll Manufacturing

Recent advances in perovskite solar cells (PSCs) have resulted in greater than 23% efficiency with superior advantages such as flexibility and solution-processability, allowing PSCs to be fabricated by a high-throughput and low-cost roll-to-roll (R2R) process. The development of scalable deposition processes is crucial to realize R2R production of flexible PSCs. Gravure printing is a promising candidate with the benefit of direct printing of the desired layer with arbitrary shape and size by using the R2R process. Here, flexible PSCs are fabricated by gravure printing. Printing inks and processing parameters are optimized to obtain smooth and uniform films. SnO2 nanoparticles are uniformly printed by reducing surface tension. Perovskite layers are successfully formed by optimizing the printing parameters and subsequent antisolvent bathing. 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene is also successfully printed. The all-gravure-printed device exhibits 17.2% champion efficiency, with 15.5% maximum power point tracking efficiency for 1000 s. Gravure-printed flexible PSCs based on a two-step deposition of perovskite layer are also demonstrated. Furthermore, a R2R process based on the gravure printing is demonstrated. The champion efficiency of 9.7% is achieved for partly R2R-processed PSCs based on a two-step fabrication of the perovskite layer.

Custom-Shaped Organic Photovoltaic Modules-Freedom of Design by Printing

Freedom of design that was introduced as organic photovoltaic (OPV) modules were fabricated by printing. As proof-of-concept, we show OPV leaf fabrication in A5 size using gravure and rotary screen printing processes for the main active layers of the OPV structure. These printing methods allow direct printing of any kind of arbitrary, two-dimensional shapes including patterning of the electric contacts thus post-patterning stages are not needed. Fabrication of custom-shaped OPV modules requires detailed information about the technical boundaries set by the manufacturing process and materials which in turn influence the layout design and R2R upscaling. In this paper, we show custom-shaped OPV modules, patterned directly in a shape of a tree leaf with an overall size of 110 cm² and an active area of 50 cm² providing a power conversion efficiency of 2.0% and maximum power of 98 mW.