Critical Role of Non-Halogenated Solvent Additives in Eco-Friendly and Efficient All-Polymer Solar Cells

Abstract

Organic solar cells (OSCs) demonstrating high power conversion efficiencies have been mostly fabricated using halogenated solvents, which are highly toxic and harmful to humans and the environment. Recently, non-halogenated solvents have emerged as a potential alternative. However, there has been limited success in attaining an optimal morphology when non-halogenated solvents (typically o-xylene (XY)) were used. To address this issue, we studied the dependence of the photovoltaic properties of all-polymer solar cells (APSCs) on various high-boiling-point non-halogenated additives. We synthesized PTB7-Th and PNDI2HD-T polymers that are soluble in XY and fabricated PTB7-Th:PNDI2HD-T-based APSCs using XY with five additives: 1,2,4-trimethylbenzene (TMB), indane (IN), tetralin (TN), diphenyl ether (DPE), and dibenzyl ether (DBE). The photovoltaic performance was determined in the following order: XY + IN < XY + TMB < XY + DBE ≤ XY only < XY + DPE < XY + TN. Interestingly, all APSCs processed with an XY solvent system had better photovoltaic properties than APSCs processed with chloroform solution containing 1,8-diiodooctane (CF + DIO). The key reasons for these differences were unraveled using transient photovoltage and two-dimensional grazing incidence X-ray diffraction experiments. The charge lifetimes of APSCs based on XY + TN and XY + DPE were the longest, and their long lifetime was strongly associated with the polymer blend film morphology; the polymer domain sizes were in the nanoscale range, and the blend film surfaces were smoother, as the PTB7-Th polymer domains assumed an untangled, evenly distributed, and internetworked morphology. Our results demonstrate that the use of an additive with an optimal boiling point facilitates the development of polymer blends with a favorable morphology and can contribute to the widespread use of eco-friendly APSCs.

Green solvent-processed organic solar cells based on a small-molecule Ir(iii) complex as electron donor materials

“…Thus, non-halogenated aromatic solvents are considered as more appropriate processing solvents for environmentally friendly photovoltaic technology. [44][45][46][47][48] In this work, for devices based on the small-molecule cyclometalated Ir(III) complex TBz3Ir donor and PY-IT polymer acceptor, three solvents CF, DCB, and XY with different boiling points (BPs) and solubility of the active layer materials were selected as the processing solvents to dissolve the D/A blends. XY showed much higher BP (B144 1C) and slightly poorer solubility to active layer materials than CF (BP: B61 1C), thus, a high-temperature spin-coating strategy was conducted to ensure concentrated D/A blended solution for XY.…”

Electronic Skin for Health Monitoring Systems: Properties, Functions, and Applications

“…One method is to regulate the composition of the material, including adjusting the proportion of the monomer and cross-linking agent of the polymer [272][273][274] and adding auxiliary materials with adhesive performance. [109,[275][276][277][278] Zhao et al used dopamine-modified oxidized hyaluronic acid to prepare . Reproduced with permission.…”

Optimization of all-polymer/Sb2Se3 tandem solar cells for enhanced efficiency: a comprehensive TCAD modeling approach

“…These all-PSCs, featuring bulk heterojunction (BHJ) photoactive layers comprising a p-type conjugated polymer donor and an n-type conjugated polymer acceptor, have garnered rising interest [14]. This interest is owed to their superior mechanical properties, thermal stability, photostability, and environmentally friendly solar energy conversion [15]. An exemplary achievement was demonstrated with the introduction of the first PSMA, PZ1, derived from polymerized IDIC-C16, which yielded a remarkable efficiency of 9.19% [16].…”