Three noncovalently fused-ring electron acceptors (FOC6-IC, FOC6-FIC, and FOC2C6-2FIC) are synthesized. Single crystals of FOC6-IC and FOC2C6-2FIC are prepared, and structure analyses reveal that the molecular backbone can be planarized via the formation of the intramolecular noncovalent interactions. These acceptor molecules can be packed closely in the solid state via π–π stacking and static interactions between the central phenylene unit and the terminal group with a distance of 3.3–3.4 Å. Besides, multiple intermolecular noncovalent interactions can be observed in the single crystal structure of the fluorinated acceptor FOC2C6-2FIC, which help increase the crystallinity of acceptors and the charge mobility of the blends. Photovoltaic devices based on FOC2C6-2FIC give a power conversion efficiency of 12.36%, higher than 12.08% for FOC6-FIC and 10.80% for FOC6-IC.

Three terpolymer donors (PL1, PL2, and PL3) employing repeating units of two popular photovoltaic polymers PM6 and D18 are synthesized by random copolymerization. The terpolymers can reduce the regio-regularity of the polymer backbones and endow them with much-enhanced solubility in nonhalogenated solvents such as o-xylene. Furthermore, along with the appearance of temperature-dependent aggregation behavior, indicating the adaptability for fabricating organic solar cells (OSCs) by eco-friendly solvent processing. Among them, PL1-based OSCs display higher and more balanced hole and electron mobilities, longer charge separation exciton lifetime, and better exciton dissociation and charge collection capabilities than the parent polymers (PM6 and D18) based ones. A power conversion efficiency of 18.14% with a very low energy loss is achieved based on terpolymer PL1, which is much higher than that of PM6 (15.16%) and D18 (16.18%). The result provides an effective way to realize high-performance nonhalogenated processing polymer donor materials.

In 2015, Zhan et al. reported the A-D-A type fused-ring electron acceptor (FREA) (ITIC), [12] which allows for a PCE of ≈7% in nonfullerene OSCs. Later, Zou et al. reported a novel A-DA′D-A-type acceptor (Y6). [13] Subsequently, Y6 and its derivatives became the most commonly used acceptor materials for fabricating high-performance OSCs, [14][15][16][17][18] which gave rise to a rapid improvement of the device performance.Typically, the strong intramolecular charge-transfer (ICT) effect in FREAs can efficiently extend the absorption spectrum to the near-infrared region. [19] Hence, high-efficiency OSCs require a widebandgap polymer donor to match with the narrow-bandgap FREAs to deliver a high short-circuit current. [20][21][22][23][24][25][26][27] However, the current donor polymer materials used for nonfullerene solar cells are initially developed to work for fullerene-based OSCs. Compared with the abundance of high-efficiency acceptor materials, high-performance polymer donor materials are scarce. To date, there are only several polymer donors (namely, PM6, [28,29] D18, [30] PTzBI-dF, [31] PTQ10, [32] PBCT-2F, [33] PBQx-TF, [34] and PNTB6-Cl [35] ) that can afford an efficiency of higher than 17%. Three regioregular benzodithiophene-based donor-donor (D-D)-type polymers (PBDTT, PBDTT1Cl, and PBDTT2Cl) are designed, synthesized, and used as donor materials in organic solar cells (OSCs). Because of the weak intramolecular charge-transfer effect, these polymers exhibit large optical bandgaps (>2.0 eV). Among these three polymers, PBDTT1Cl exhibits more ordered and closer molecular stacking, and its devices demonstrate higher and more balanced charge mobilities and a longer charge-separated state lifetime. As a result of these comprehensive benefits, PBDTT1Cl-based OSCs give a very impressive power conversion efficiency (PCE) of 17.10% with a low nonradiative energy loss (0.19 eV). Moreover, PBDTT1Cl also possesses a low figure-of-merit value and good universality to match with different acceptors. This work provides a simply and efficient strategy to design low-cost highperformance polymer donor materials.

Phototheranostics constitute an emerging cancer treatment wherein the core diagnostic and therapeutic functions are integrated into a single photosensitizer (PS). Achieving the full potential of this modality requires being able to tune the photosensitizing properties of the PS in question. Structural modification of the organic framework represents a time-honored strategy for tuning the photophysical features of a given PS system.Here we report an easy-to-implement metal selection approach that allows for fine-tuning of excited-state energy dissipation and phototheranostics functions as exemplified by a set of lanthanide (Ln = Gd, Yb, Er) carbazole-containing porphyrinoid complexes. Femto-and nanosecond time-resolved spectroscopic studies, in conjunction with density functional theory calculations, revealed that the energy dissipation pathways for this set of PSs are highly dependent on the energy gap between the lowest triplet excited state of the ligand and the excited states of the coordinated Ln ions. The Yb complex displayed a balance of deactivation mechanisms that made it attractive as a potential combined photoacoustic imaging and photothermal/photodynamic therapy agent. It was encapsulated into mesoporous silica nanoparticles (MSN) to provide a biocompatible construct, YbL@MSN, which displays a high photothermal conversion efficiency (η = 45%) and a decent singlet oxygen quantum yield (Φ Δ = 31%). Mouse model studies revealed that YbL@MSN allows for both photoacoustic imaging and synergistic photothermal-and photodynamic-therapy-based tumor reduction in vivo. Our results lead us to suggest that metal selection represents a promising approach to fine-tuning the excited state properties and functional features of phototheranostics.

NIR fluorescent palladium(ii) complexes were firstly achieved by the formation of M–C bonds and reducing the π-conjugation of macrocyclic ligands. The capability of in vitro and in vivo bioimaging has been demonstrated.