Amine‐Based Polar Solvent Treatment for Highly Efficient Inverted Polymer Solar Cells

Abstract

The interfacial dipolar polarization in inverted structure polymer solar cells, which arises spontaneously from the absorption of ethanolamine end groups, such as amine and hydroxyl groups on ripple-structure zinc oxide (ZnO-R), lowers the contact barrier for electron transport and extraction and leads to enhanced electron mobility, suppression of bimolecular recombination, reduction of the contact resistance and series resistance, and remarkable enhancement of the power conversion efficiency.

Solution-derived poly(ethylene glycol)-TiO x nanocomposite film as a universal cathode buffer layer for enhancing efficiency and stability of polymer solar cells

“…Contact angle (CA) measurements were recorded by using a CA System (DSA100, Kruss Co., Germany). V L [6,18], where ε 0 is the permittivity of free space, ε r is the dielectric constant of the material, μ is the electron carrier mobility, V is the voltage drop across the device (V = V app -V bi , where V app is the applied voltage to the device, and V bi is the built-in voltage), and L is the thickness of the organic film (~89 and 74 nm for the device with PEG-TiO x and TiO x , respectively). Then the devices were also kept overnight.…”

Highly efficient inverted polymer light-emitting diodes using surface modifications of ZnO layer

“…A 0.75-M ZnO-R solution was synthesized by dissolving zinc acetate dehydrate [Zn(CH 3 COO) 2 2H 2 O] in 2-methoxyethanol and ethanolamine co-solvents. This solution was stirred at 60°C for 30 min to yield a clear and homogeneous solution [31][32][33] . The ZnO-R precursor solution was spincast onto cleaned FTO substrates after a 30-min UV-ozone treatment and heated to 400°C with a heating rate of 20°C per minute (ZnO-R1) or 10°C per minute (ZnO-R2).…”

“…The efficiency of iPLEDs with ZnO-R was further increased by the application of an amine-based solvent treatment to the ZnO-R. We have demonstrated that applying a polar solvent treatment to the ZnO surface reduces the contact barrier between the active polymer and the ZnO layer because of the interfacial negative dipole effect, which is created spontaneously by the absorption of the amine (NH 2 ) and hydroxyl (OH) groups of EA on ZnO-R, enhancing the electron extraction by suppression of recombination of the electron and hole carriers 31 . The interfacial negative dipolar polarization that the nitrogen atoms and OH groups with and (b) with the 2-ME þ EA interlayer (R rms ¼ 1.21 nm) and of (c) ZnO-R1 (R rms ¼ 3.11 nm) and (d) ZnO-R2 layers with the 2-ME þ EA interlayer (R rms ¼ 13.1 nm).…”

“…The iPLEDs were fabricated via the sequential deposition of ZnO, 2-ME þ EA, F8BT, MoO 3 and Au onto an FTO-coated glass substrate; this process is described in detail in the Methods section. Although the glass WG mode remains inside the device and therefore cannot contribute to the total light extraction, the ZnO/organic WG modes can be stimulated to be out-coupled by the ZnO-R. rate during annealing and the concentration of the ZnO solution [31][32][33] 34,35 . ZnO layers with a ripple-shaped nanostructure of lesser height and narrower width (ZnO-R1) were developed when the spin-coated ZnO samples were heated to 400°C at a rapid heating rate (20°C per minute), whereas structures of higher height and broader width (ZnO-R2) were fabricated using a slower heating rate (10°C per minute).…”

Towards High Performance Organic Photovoltaic Cells: A Review of Recent Development in Organic Photovoltaics

“…Faster decay kinetics after methanol treatment indicated a faster extraction of the mobile carrier, which was detected by the internal field-dependent transient photoconductivity measurement. In addition, Lee et al reported that using 2-methoxyethanol and ethanolamine co-solvent to modify the ZnO interface in OPV based on PTB7/PCBM BHJ could lead to increased electron mobility, suppressed bimolecular recombination and minimized contact resistance [144].…”