Bendable ITO-free Organic Solar Cells with Highly Conductive and Flexible PEDOT:PSS Electrodes on Plastic Substrates

Flexible and transparent electrodes have great potential for photon transmission and charge-carrier collection for next generation electronics compared to rigid electronics with indium tin oxide (ITO)-coated glass substrates. This study describes a comprehensive study of the electrical, morphological, optical, structural, and mechanical properties of poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) films treated by methanol and methanesulfonic acid (MSA), which are coated on hydrophobic flexible plastic substrates. Such a film coated on hydrophobic plastic substrates exhibits a high conductivity up to 3560 S cm^–1 and a good mechanical flexibility. Moreover, the use of the films to fabricate bendable ITO-free organic solar cells (OSCs) integrated on plastic substrates was presented. The bendable devices based on P3HT:PCBM not only exhibit a high power conversion efficiency (PCE) up to 3.92%, which is comparable to 4.30% of the rigid devices with ITO-coated glass substrates, but also keep about 80% in PCE of the initial value after 100 time bending with a bending radius of 14 mm in the ambient atmosphere. This work provides a novel route to dramatically improve the conductivity of PEDOT:PSS electrodes, as well as the mechanical flexibility of highly efficient organic electronics with the flexible electrodes

Transfer-Printed PEDOT:PSS Electrodes Using Mild Acids for High Conductivity and Improved Stability with Application to Flexible Organic Solar Cells

Highly conductive, flexible, and transparent electrodes (FTEs) of PEDOT:PSS films on plastic substrates have been achieved using strong acid treatments. However, it is rare to realize a performance attenuation of PEDOT:PSS FTEs on plastic substrates and flexible optoelectronic devices because of strong acid residues in the PEDOT:PSS matrix. Herein, we develop a feasible transfer-printing technique using mild acids. Because of a mild and weak property of these acids and less acid residues in PEDOT:PSS matrix, the transferred PEDOT:PSS FTEs exhibited a significant enhancement in stability, conductivity (3500 S cm^–1), transparency, and mechanical flexibility on plastic substrates. Flexible organic solar cells with the FTEs also showed a remarkable enhancement in power conversion efficiency and stability in the ambient atmosphere. It is expected that the novel transfer-printing technique for making PEDOT:PSS FTEs is also useful in many other types of flexible optoelectronic devices

Decreasing the Viscosity in CO₂ Capture by Amino-Functionalized Ionic Liquids through the Formation of Intramolecular Hydrogen Bond

A strategy for decreasing the viscosity variation in the process of CO₂ capture by amino-functionalized ionic liquids (ILs) through the formation of intramolecular hydrogen bond was reported. Different with the dramatic increase in viscosity during CO₂ uptake by traditional amino-functionalized ILs, slight increase or even decrease in viscosity was achieved through introducing a N or O atom as hydrogen acceptor into amino-functionalized anion, which could stabilize the active hydrogen of produced carbamic acid. Quantum chemical calculations and spectroscopic investigations demonstrated that the formation of intramolecular hydrogen bond between introduced hydrogen acceptor and carbamic acid was the key to avoid the dramatic increase in viscosity during the capture of CO₂ by these amino-functionalized ILs

Highly Efficient Non-Fullerene Organic Solar Cells Using 4,8-Bis((2-ethylhexyl)oxy)benzo[1,2‑<i>b</i>:4,5‑<i>b</i>′]dithiophene-Based Polymers as Additives

Electron acceptor units play an important role in the design of donor–acceptor (D–A) type polymers for efficient organic solar cells (OSCs). In this report, with the oxidation of the thiophene moiety, the electron-rich 4,8-bis­((2-ethylhexyl)­oxy)­benzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­dithiophene (BDT) unit was tuned into electron-deficient 4,8-bis­((2-ethylhexyl)­oxy)­benzo­[1,2-<i>b</i>:4,5-<i>b</i>′]­dithiophene 1,1,5,5-tetraoxide (BDTO) unit. Two novel polymers of PBDTO and PBDTO-T based on BDTO unit were synthesized and employed as additives in efficient non-fullerene OSCs with the active layer consist of PBDB-T and IT-M. With doping 1% PBDTO or PBDTO-T, the power conversion efficiency (PCE) of the prepared OSCs increased from 10.31% to 11.47% or 11.12%, respectively. These two polymers can afford cascaded energy levels and smooth the surface of the active layer, which are beneficial for better carrier transportation and separation. Our results open a new avenue to construct electron acceptor backbone in the design of D–A type polymers for OSCs