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Two novel unfused acceptors, ABBT-BO(DT), featuring 1,4-azaborine have been synthesized. ABBT-BO based OSCs achieved an optimal PCE of over 10% for higher exciton dissociation, improved carrier transport and suppressed charge recombination.

Two polymerized small molecule acceptors with wide bandgaps of ∼1.65 eV and high-lying LUMO energy levels above −3.70 eV were designed by introducing a novel terminal unit. Efficient all-PSCs with high VOC over 1.10 V were achieved.

A facile depolymerization reaction of polymerized small molecule acceptors (PSMAs) is developed for efficiently recovering the polymeric monomers in various circumstances, showing potential on decreasing the cost of PSMA-based all-PSCs.

The 3,4-ethylenedithio thiophene donor is used to construct S–D–A–D–S NIR-II nanofluorophores, which can exhibit an improved fluorescent quantum yield and enhanced brightness for in vivo imaging of mouse cerebral vessels.

To develop environmentally friendly solvent processed high performance polymer solar cells (PSCs), an alcohol soluble narrow-band-gap conjugated polymer PCDTBT-N and an alcohol soluble C70 fullerene derivative PC71BM-N, which were functionalized with pendant tertiary amino groups, were developed and used as active layers in PSCs and as buffer layers in metal–semiconductor interfaces. Though solar cells with active layers containing amino groups showed no photovoltaic properties regardless of the processing conditions, both PCDTBT-N and PC71BM-N performed well as buffer layers to improve electron collection in PSCs. Space charge limited current (SCLC), field effect transistor (FET) and cyclic voltammetry (CV) studies revealed that the amino groups act as hole traps and disable hole transport in active layers. Moreover, ultraviolet photoelectron spectroscopy (UPS) indicates electronic structure changes and Fermi level shifts upon complexation of amino groups and the fullerene core, which may diminish the electron-accepting capacity of fullerenes, and may potentially provide a different kind of hole trap in the devices. The underlying mechanisms of the puzzling behavior of PCDTBT-N and PC71BM-N in different layers of PSCs were studied by numerical simulation, which indicates that hole traps distributed in the BHJ layer reduce device performance, conversely hole traps concentrated near the metal electrode can improve device performance. Besides, the formation of an amino group:C70 complex is another important cause of the performance improvements of the resulting solar cells using PCDTBT-N and PC71BM-N as buffer layers, due to the reduced transport loss for efficient electron collection through the n-doping of PC71BM at the interface of the buffer layer and the active layer.

A series of narrow band gap donor–acceptor type conjugated copolymers based on 2,6-linked anthracene derivatives are synthesized via Suzuki copolymerization. The resulting copolymers typically exhibit dual absorption characteristics in both solution and as thin films with optical band gaps in the range of 1.85–2.13 eV. By varying the substitutions from alkyloxy to aromatic thienyl and phenyl groups in the 9,10-positions of the anthracene unit, the constructed two-dimensional 2,6-linked anthracene structures lead to broader absorption, lower-lying highest occupied molecular orbitals, as well as improved charge carrier mobilities of the resulting copolymers relative to the alkyloxy side chain substituted counterparts. Additionally, it was found that the sizes of the substitutions in the benzo[c][1,2,5]thiadiazole acceptor also play an important role in the optoelectronic properties of these anthracene based conjugated copolymers. The best polymer solar cell device with a power conversion efficiency of 4.34% and a high open circuit voltage of 0.98 V was realized based on the resulting materials. Our results indicate that substantial optimization in the sizes and patterns of substitutions of both the 2,6-linked anthracene donor and benzo[c][1,2,5]thiadiazole acceptor may potentially lead to high performance narrow band gap copolymers for solar cell applications.