Highly Efficient, Mechanically Flexible, Semi‐Transparent Organic Solar Cells Doctor Bladed from Non‐Halogenated Solvents

Abstract

All‐solution deposited, ITO‐free organic solar cells comprising hybrid top and bottom electrodes and ternary polymer:fullerene photo‐active layers are investigated. A printed micro silver mesh and conductive PEDOT:PSS are employed as bottom electrode on a mechanically flexible PET substrate, whereas the top electrode features highly conductive PEDOT:PSS with dispersed silver nanowires. The highly efficient ternary polymer:fullerene absorber blend PffBT4T‐2OD:PC61BM:PC71BM and all other functional layers are doctor bladed from non‐halogenated solvents in order to comply with the requirements of industrial device fabrication. The semi‐transparent solar cells yield maximum power conversion efficiencies of 6.6% on active areas ≤ 0.1 cm2 and 5.9% on active areas > 1 cm2. Omitting additional bus bars for charge extraction grants the solar cells a homogeneous appearance and transparency perception.

Thermal Stabilization of the Bulk‐Heterojunction Morphology in Polymer:Fullerene Solar Cells Using a Bisazide Cross‐Linker

“…The corresponding data ( J – V curves, optical microscope and AFM images) are summarized in Figure S10 and Table S5. Finally, we investigated the highly crystalline polymer poly[(5,6‐difluoro‐2,1,3‐benzothiadiazole‐4,7‐diyl)‐alt‐(3,3‴‐di(2‐octyldodecyl)‐2,2′;5′,2″;5″,2‴‐quaterthiophene‐5,5‴ diyl)] (PffBT4T‐2OD) that was deposited from o ‐xylene: p ‐anisaldehyde solution . During 40 h of thermal annealing at 120 °C, the PCE was reduced from 8.2% to 2.3% in absence of the crosslinker, which is accordance with earlier literature reports on the low miscibility of PffBT4T‐2OD and fullerenes and, as such, strong degradation .…”

Solar Glasses: A Case Study on Semitransparent Organic Solar Cells for Self‐Powered, Smart, Wearable Devices

“…It is also suitable for depositing absorber layers with thicknesses beyond 250 nm on a large scale and can be processed in air without detrimental effects on the device performance or stability . The absorber blend was dissolved and processed from a mixture of the solvent o ‐xylene and the co‐solvent p ‐anisaldehyde, which forms a very suitable and fast drying alternative to the often‐used toxic halogenated solvents …”

Organic Solar Modules: Fully Doctor Bladed on Glass in Air

“…Hence, the use of non‐halogenated and eco‐compatible solvents is pivotal for the cost‐efficient industrial fabrication of solar cells. Recently, we reported excellent solar cell performance upon depositing the light‐harvesting polymer PffBT4T‐2OD together with a [6,6]‐phenyl C 61 ‐butyric acid methyl ester/[6,6]‐phenyl C 71 ‐butyric acid methyl ester (PC 61 BM/PC 71 BM) fullerene mixture from the eco‐compatible solvent mixture o ‐xylene/ p ‐anisaldehyde (AA) . In this work, we used this eco‐friendly solvent combination to deposit an absorber blend comprising the light‐harvesting polymer PBTZT‐stat‐BDTT‐8 and commercially available technical‐grade PCBM, the latter intrinsically containing approximately 90 % of PC 61 BM and 10 % of PC 71 BM.…”

“…Often, metal bus bars are employed to enhance the lateral conductivity of the electrodes . Recently, we demonstrated large‐area, high‐performance plastic solar cells comprising two printable transparent electrodes without clearly visible bus bars that not only improved light harvesting by avoiding shadowing effects but also enhanced the solar cells’ esthetic appearance …”