Qidan Ling

Non-halogenated low-toxicity polymers demonstrate significant commercialization potential for organic solar cells (OSCs), owing to their advantageous processing characteristics. However, high-performance non-halogenated polymer donors are still limited. Herein, dithienophthalimide (DPI)-based monomers bearing various side chains have been synthesized at low cost. And then, a series of BDT-DPI-based non-halogenated polymer donors (PBDT-DPIs) were designed and obtained by synergistically tuning the alkyl side chains on both DPI and BDT units, in which thiophene served as a π-bridge, BDT with various side chains (R₁) served as the D unit, and DPI with various side chains (R₂) served as the A unit. The effects of alkyl side chains on the polymers’ optical absorption spectra, electronic and morphological properties, and photovoltaic performance were investigated to understand the relationship between the structure and photovoltaic (PV) performance. It is found that alkyl side chain lengths have negligible impact on optical absorption spectra due to their same backbones, but have profound effects on their aggregation and crystallinity in the solid state. The length of alkyl side chains has a significant influence on the active layer morphology, charge transport properties, and device performance when blended with the non-fullerene acceptor BTP-eC9. As a result, through fine-tuning the alkyl side chains, a PBDT_(8,10)-DPI_(4,6)-based device exhibited the highest PCE of 14.56%, with an open-circuit voltage of 0.85 V, a short-circuit current density of 24.76 mA cm⁻², and a fill factor of 69.05%. Our study demonstrated that tailoring the side chain on both BDT and DPI units could optimize crystallinity, aggregation and miscibility for developing high-performance non-halogenated polymer donors.

Organic–inorganic hybrid perovskites (OIHPs) with ultralong organic phosphorescence (UOP) have attracted considerable attention because of their unique optical properties and long phosphorescence lifetimes. However, the development of amorphous UOP perovskites with excellent processability remains a significant challenge. Herein, N-aminoethyl piperazine is employed as a non-conjugated ligand to synthesize amorphous Cd-based OIHPs (named AC-A), which exhibit white-light emission and green phosphorescence originating from clusters formed by organic ligands. Owing to their ultralong phosphorescence lifetime, the AC-A perovskites display a long green afterglow lasting for up to 8 s. The afterglow color can be tuned to orange and red by doping inorganic and organic guest species, respectively. Furthermore, flexible and adhesive thread-like heterostructured composites with different afterglow colors are prepared by coating polylactic acid on AC-A and are successfully applied in a programmable information encryption system. This work not only utilizes rigid inorganic octahedra to protect organic clusters and achieve UOP in amorphous hybrid perovskites but also provides a novel design strategy and example for the development of amorphous, flexible cluster luminescent materials with multi-color afterglow.

Non-conjugated polysiloxane nanomaterials with amino and urea groups show persistent cluster-induced phosphorescence regulated by doping different small molecules, and fluorescence/phosphorescence dual responses to Ag⁺ in aqueous solutions.

A novel polyimide containing Eu complex with bipyridine unit in main chain was synthesized via the polycondensation and coordination reaction. The memory device based on the Eu-bonded polyimide showed nonvolatile memory behavior with low threshold voltage, high current ratio and good long-term stability. The introduction of Eu-bipyridine complex tuned and improved the memory performance of the device.

In the past decade, the study on organic solar cells (OSCs) has made great progress. For commercial application, achieving high efficiency OSCs with the prominent stability is a crucial issue. Here, two crosslinkable vinyl-functionalized D–A–D–D₁-type polymers PM6-Ax (x: 5 or 15) were successfully synthesized by introducing a crosslinkable benzodithiophene (D₁) unit with vinyl functionality into the D–A polymer PM6. As expected, the un-crosslinked PM6-A5:Y6-based OSC process an outstanding PCE (15.20%) without additives, which is higher than that of the reference PM6:Y6-based OSCs (13.65%) by the D–A–D–D₁ strategy. It is found that polymers PM6-Ax can be crosslinked to some extent after annealing at 150 °C for a certain period of time. Meanwhile, by thermal crosslinking of the active layer, the PM6-Ax:Y6-based devices were fabricated and the stability was studied. Reference PM6:Y6-based devices were also fabricated. As a result, crosslinked PM6-A5:Y6-based devices retained 91.0% of the initial PCE under 48 h of continuous 60 °C thermal aging and 92.8% of the initial PCE under 72 h continuous white LED light illumination, whereas the reference PM6:Y6-based devices retained 81.9% and 72.7% under the same aging conditions. Moreover, crosslinked PM6-A5:Y6-based devices showed superior shelf-life stability over the reference devices. These results demonstrate that crosslinking of the PM6-A5:Y6-based active layer can significantly boost overall stability (including thermal-stability, photo-stability, and storage-stability) of the OSCs.

We developed novel D–A–D–D₁-type polymers with unequal D and A units by incorporating a third component into the backbone of PM6 for enhanced short-circuit current density.

A kind of metal-free organic ammonium halides characterized by a unique 2D layered structure show colorful ultralong phosphorescence. Phosphorescent quantum yield (up to 19%) and lifetime (up to 1.7 s) can be tuned by doping with different phosphors.

Simple molecule TIM with planar conformation and rich heteroatoms exhibits white emission and yellow phosphorescence for space conjugation. TIM powder can be employed as a single-component material to fabricate WLEDs driven by both UV and blue chips.