Design of Multilayered Nanostructures and Donor–Acceptor Interfaces in Solution‐Processed Thin‐Film Organic Solar Cells

Abstract

Multilayered polymer thin‐film solar cells have been fabricated by wet processes such as spin‐coating and layer‐by‐layer deposition. Hole‐ and electron‐transporting layers were prepared by spin‐coating with poly(3,4‐ethylenedioxythiophene) oxidized with poly(4‐styrenesulfonate) (PEDOT:PSS) and fullerene (C60), respectively. The light‐harvesting layer of poly‐(p‐phenylenevinylene) (PPV) was fabricated by layer‐by‐layer deposition of the PPV precursor cation and poly(sodium 4‐styrenesulfonate) (PSS). The layer‐by‐layer technique enables us to control the layer thickness with nanometer precision and select the interfacial material at the donor–acceptor heterojunction. Optimizing the layered nanostructures, we obtained the best‐performance device with a triple‐layered structure of PEDOT:PSS|PPV|C60, where the thickness of the PPV layer was 11 nm, comparable to the diffusion length of the PPV singlet exciton. The external quantum efficiency spectrum was maximum (ca. 20%) around the absorption peak of PPV and the internal quantum efficiency was estimated to be as high as ca. 50% from a saturated photocurrent at a reverse bias of −3 V. The power conversion efficiency of the triple‐layer solar cell was 0.26% under AM1.5G simulated solar illumination with 100 mW cm−2 in air.

Graded Donor‐Acceptor Heterojunctions for Efficient Organic Photovoltaic Cells

“…The fi ll factor (FF) decreases with thickness for all three ZEP GHJs due to a reduction in the charge collection effi ciency with increasing thickness. [ 27 ] The FF for the ZEP (1:3) gradient is lower than that of the ZEP (1:4) and ZEP (1:5) gradients. This trend refl ects the behavior of the electron and hole mobilities of SubPc and C 60 upon dilution in a mixture.…”

Influence from the sulfonate group () on the conversion process and emission efficiency of poly(p-phenylene vinylene)

“…In addition to an advantageous processability, the luminescence properties were also enhanced because less structural defects were generated [12]. Recently, Ogawa et al made use of the low PTHT/DBS conversion concept to enhance the photovoltaic effect of multilayer PPV photocells [13][14][15]. Furthermore, with DBS one can produce layer-by-layer films of PPV with excellent control of film architecture and then control the emission properties [16].…”

Layer double hydroxide and sodium montmorillonite multilayer coatings for the flammability reduction of flexible polyurethane foams

“…By submersing a substrate (e.g., PUF) into positively and negatively charged polyelectrolyte and/or nanoparticle solutions, a positive–negative pairing layer, called a bilayer (BL), will adhere to the surface by electrostatic attractions . Other forces have also been used to promote LbL‐coating growth, such as hydrogen bonds, covalent bonds, and donor/acceptor interactions . Besides fire‐resistant coatings, this technology has been used for gas barriers, antimicrobials, and electrically conductive coatings …”