Annealing‐Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting Process

Abstract

Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller‐painted film – composed of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) – has a smoother surface than a spin‐coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller‐painted active layer contribute to enhanced and balanced charge‐carrier mobility. Consequently, the roller‐painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing‐free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi‐1,8‐thiol. Since the addition of octanedi‐1,8‐thiol induces phase separation between P3HT and PCBM and the roller‐painting process induces crystallization of P3HT and PCBM, a PCE of roller‐painted PSCs of up to 3.8% is achieved without post‐annealing. A PCE of over 2.7% can also be achieved with 5 cm2 of active area without post‐annealing.

Efficient Inverted Polymer Solar Cells with Directly Patterned Active Layer and Silver Back Grating

“…The fabrication process itself can be in principle scaled up. The nanoimprinted method to fabricate the back grating electrode is highly compatible with the roller painting approach 44,45 in mass producing PSCs. Hence, this method is promising in realizing high-performance polymer solar cells in industrial processes.…”

A comparative assessment of surface microstructure and electrical conductivity dependence on co-solvent addition in spin coated and inkjet printed poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS)

“…The potential for increased flexibility, performance and cost effectiveness over the more common inorganic materials has generated much interest in the fields of light emitters [1][2][3], high volume photovoltaics [4][5][6][7][8] and RF antennae [9][10] all of which can take advantage of the new properties…”

Efficiency improvement in organic solar cells by inserting a discotic liquid crystal

“…According to literature reports, during heating, the molecule HAT4 undergoes a transition from a crystalline phase to a columnar hexagonal mesophase (Col h ) at 88.6 1C followed by isotropization at 145.6 1C [20]. A hexagonal columnar mesophase appeared between the melting and clearing points of the triphenylene derivative [21][22][23]. Pure HAT4 forms only a plastic hexagonal columnar (Col hp ) mesophase, which is characterized by three-dimensional crystal-like order in a hexagonal lattice, while the disks within the columns are able to rotate about the columnar axis [24][25].…”