Highly Efficient and Operational Stability Polymer Solar Cells Employing Nonhalogenated Solvents and Additives

Abstract

The power conversion efficiencies (PCEs) of potential polymer solar cells have been shown to rapidly exceed 15%. However, these high-performance devices are based on halogenated solvents that pose a significant hazard to the atmospheric environment and human beings. The use of nonhalogenated solvents makes the device less efficient because of its solubility issues. In this work, we report high-efficiency devices utilizing PffBT4T-2OD and [6,6]-phenyl C butyric acid methyl ester system from nonhalogenated solvents such as o-xylene ( o-XY) and 1-methylnaphthalene (Me) hydrocarbon solvent. When Me was used as the additive, the PCE of prepared devices improved from 1.83 to 10.13%, which is rather higher than that of the devices processed with traditional solvents combined with chlorobenzene and 1,8-diiodooctane (8.18%). Both atomic force microscopy and transmission electron microscopy confirmed that after nonhalogen solvents are treated, a more finely phase-separated dense morphology of active layers than after halogen solvents. At the same time, grazing incident wide-angle X-ray scattering patterns show that the combination of nonhalogenated solvents o-XY and Me ingeniously formed an ordered crystal and π-π stacking. Also, the stability of devices prepared from nonhalogenated solvents was significantly better than that of halogenated solvents under continuous illumination in the air without encapsulation.

Air‐Processed, Stable Organic Solar Cells with High Power Conversion Efficiency of 7.41%

“…In addition, the broad peak at ≈14.0 nm −1 was enhanced because of the aggregation of PC 61 BM along both the OOP and IP directions . In a word, after thermal annealing, the enhanced crystallinity and crystal orientation of photoactive films were mainly due to the strong lamellar stacking and the aggregation of PC 61 BM, which was consistent with the observed coarser and prolonged fibrillary morphology of PDPPPTD polymer in AFM phase images . Therefore, thermal annealing in our case was undesirable, which would indeed simplify device fabrication process.…”

A 3‐Fluoro‐4‐hexylthiophene‐Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco‐Friendly Nonfullerene Organic Solar Cells

“…However, the device processed by CB/DIO, its PCE dropped by 45% after 2 h of testing. It can be estimated that nonhalogenated solvents cause less damage to donor and acceptor materials in air with the light illumination because of the stable molecular structures of these solvents consisting of stable carbon and hydrogen atoms …”

“…It can be estimated that nonhalogenated solvents cause less damage to donor and acceptor materials in air with the light illumination because of the stable molecular structures of these solvents consisting of stable carbon and hydrogen atoms. [72][73][74] In this study, we designed and synthesized WBG donor polymers employing a simultaneous fluorination and alkylation technique using BDT-Th (D-A), P(fTh-BDT)-C6 and P(fTh-2DBDT)-C6 to produce highly efficient NFOSCs. By simultaneously introducing fluorine and alkyl chains into the polymers, both polymers achieved good balance between solubility and intermolecular interactions.…”

From fullerene acceptors to non-fullerene acceptors: prospects and challenges in the stability of organic solar cells

“…Promisingly, the necessity of using solvent additives to reach high photovoltaic performances can be effectively negated by the selection of an appropriate host solvent, thereby side-stepping the adverse effects of these solvent additives on device stability. [157][158][159] Other processing parameters can also affect OSC stability, most commonly due to differing morphological stabilities. On a laboratory scale, the vast majority of OSCs utilise spin-coating to deposit the active layer.…”