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Low-bandgap nonfullerene acceptors (NFAs) offer a unique potential for photovoltaic (PV) applications, such as transparent PV and agrivoltaics. Evaluating each new PV system to achieve the optimum thickness, microstructure, and device performance is, however, a complex multiparametric challenge with large time and resource requirements. Herein, the PV potential of low-bandgap donor and NFA materials by combining high-throughput screening and statistical methods is evaluated. The use of thickness gradients (20–600 nm) facilitates the fabrication of more than 2000 doctor-bladed devices from 24 different low-bandgap blend combinations. The corresponding power conversion efficiencies varies significantly, from 0.06% to 10.45% across materials and thicknesses. The self-consistency of the large dataset allows to perform a parameter sensitivity study as well as parameter correlation analysis. These reveal that the choice of materials and energy alignment-related features (i.e., electron affinity offset, ionization energy offset, bandgap, and energy loss) has the largest influence on final device performance, while processing conditions appear less important for the final efficiencies. Our study demonstrates that high-throughput experimentation is a perfect match for correlation analyses in order to gain a statistically meaningful understanding of these systems, potentially accelerating the discovery of new materials.

[EN] Covalent organic Frameworks (COFs) are a class of crystalline macromolecular materials build-up by monomers with specific symmetries or functionalities. There are important limitations in the synthesis of highly ordered COFs, such as the shape and packing of the building blocks. Thus, the presence of fluorine atoms that lie perpendicular to the bisecting plane of BODIPY derivatives together with the presence of four bulky methyl groups could hinder the crystallization process in COF synthesis. For that reason, BODIPY-based COFs are rarely incorporated to COF networks. In this work, following the mixed linker strategy, a pre-synthetic method to dope COF structures with BODIPY units was developed. The materials have been processed into fluorescent Covalent Organic Nanosheets (CONs) with defined particle-size distributions around 100 nm, suitable for cellular biomedical applications. The viability of the CONs was evaluated using Sk-Mel-103 cells, demonstrating the internalization showing 100% cell viability. We envisage that this work could accelerate the discovery of new COF-based materials for biomedical sciences.

The pyrolysis of organic precursors to produce heteroatomic-doped carbonaceous materials has emerged as a powerful tool to construct metal-free heterogeneous electrocatalysts due to their low cost and their environmental friendliness. However, the lack of control in the atomic positions or the location of the chemical functionalities makes it difficult to establish structure–property relationships. Herein, we report an easy strategy to compare the electrocatalytic oxygen reduction reaction (ORR) performance of metal-free and nonpyrolyzed materials by postsynthetic modification of covalent organic frameworks (COFs) via click-chemistry. This method facilitates the evaluation of different active centers using materials with the same morphology and prevents active site agglomeration by covalently anchoring these moieties inside of a porous and crystalline framework. In this study we developed a series of diimide-based materials (XDI0.17-COFs) with a loading of 7.65 × 10–4 mol of active site/mg of host COF. The bulk COFs have been delaminated to perform electrode modification by drop-casting. The electrocatalytic response toward the ORR has been studied in alkaline media obtaining the best results for the NDI0.17-COF with an onset potential of 0.77 V (vs reversible hydrogen electrode, RHE) and a limiting current of 4.2 mA/cm2 by a preferred pathway toward water electroreduction. Finally, an adequate combination of density functional theory with the thermochemical Gibbs free energy formalism has been used to theoretically rationalize the ORR mechanism in these metal-free and nonpyrolyzed materials. We have obtained theoretical ORR overpotentials for each COF system agreeing with the experimental observation, which correlate with the ability of the NDI, BzDI, and PDI molecular blocks to accommodate electrons. Our work provides a guideline on how to study the electrocatalytic performance of different organic moieties in metal-free and non-pyrolyzed COFs avoiding their de no

While it is widely recognized that microstructure plays an important role in the performance of organic photovoltaics (OPV), systematic studies are often challenging, as varying the molecular packing through typical chemical means (such as sidechain tuning) often affects the molecular energy levels, thus preventing a clear correlation. In this work we present the synthesis of three perylene imide (PI) based electron acceptors with almost identical energy levels, but distinct packing tendencies. We confirm our initial hypothesis by measuring solution and solid-state absorption, and cyclic voltammetry as well as characterizing the films by grazing incidence wide angle X-ray scattering (GIWAXS). In a second step, we repeat the characterization of the three materials in blends with two polymer donors, namely PCDTBT or PBDBT, whose energy levels are well aligned with those of the PI acceptors, and which, additionally, exhibit different degrees of structural order. We show how the initial strong difference between acceptors is partially blurred in blends, but still critical. Finally, we correlate our structural data with OPV devices made with the corresponding six blends. Our data suggest that a good donor acceptor marriage should ensure good energy alignment but also exhibit complementary crystallization tendencies of the two components.

[Abstract] While it is widely recognized that microstructure plays an important role in the performance of organic photovoltaics (OPV), systematic studies are often challenging, as varying the molecular packing through typical chemical means (such as sidechain tuning) often affects the molecular energy levels, thus preventing a clear correlation. In this work we present the synthesis of three perylene imide (PI) based electron acceptors with almost identical energy levels, but distinct packing tendencies. We confirm our initial hypothesis by measuring solution and solid-state absorption, and cyclic voltammetry as well as characterizing the films by grazing incidence wide angle X-ray scattering (GIWAXS). In a second step, we repeat the characterization of the three materials in blends with two polymer donors, namely PCDTBT or PBDBT, whose energy levels are well aligned with those of the PI acceptors, and which, additionally, exhibit different degrees of structural order. We show how the initial strong difference between acceptors is partially blurred in blends, but still critical. Finally, we correlate our structural data with OPV devices made with the corresponding six blends. Our data suggest that a good donor acceptor marriage should ensure good energy alignment but also exhibit complementary crystallization tendencies of the two components.

While it is widely recognized that microstructure plays an important role in the performance of organic photovoltaics (OPV), systematic studies are often challenging, as varying the molecular packing through typical chemical means (such as sidechain tuning) often affects the molecular energy levels, thus preventing a clear correlation. In this work we present the synthesis of three perylene imide (PI) based electron acceptors with almost identical energy levels, but distinct packing tendencies. We confirm our initial hypothesis by measuring solution and solid-state absorption, cyclic voltammetry as well as characterizing the films by grazing incident wide angle X-ray scattering (GIWAXS). In a second step, we repeat the characterization of the three materials in blends with two polymer donors, namely PCDTBT or PBDBT, whose energy levels are well aligned with those of the PI acceptors, and which, additionally, exhibit different degrees of structural order. We show how the initial strong difference between acceptors is partially blurred in blends, but still critical. Finally, we correlate our structural data with OPV devices made with the corresponding six blends. Our data suggest that a good donor acceptor marriage should ensure good energy alignment but also exhibit complementary crystallization tendencies of the two components.

A conjugated poly(azomethine) network based on ambipolar terthiophene¿naphthalimide assemblies has been synthesized and its electrochemical and UV-vis absorption properties have been investigated. The network has been found to be a promising candidate for the photocatalytic degradation of organic pollutants in aqueous media.

In this work, a series of naphthalimide fused thienopyrazine derivatives was designed, and their synthesis and characterization are reported herein. The interaction of this building block with a donor terthiophene fragment laterally substituted by a series of donor and acceptor constituents was analyzed in depth. This strategy was proven to efficiently modulate both the energy and topology of the frontier molecular orbitals involved in the charge transport mechanism. The interplay between the donor and acceptor strengths of the different units composing the material structure is thus essential to efficiently modulate charge carriers and transport properties and to finely tune the optical and electronic structures of the presented organic semiconductors.