Spiro[fluorene-9,9′-xanthene] has received great attention due to its unique structure and possesses wide applications in the field of material chemistry. Herein, we highlighted low-cost, stable and high-performance spiro[fluorene-9,9′-xanthene] derivatives for organic electronics.

Advances in the synthesis of low bandgap (E _g < 1.5 eV) conjugated polymers has produced organic materials capable of absorbing near-infrared (NIR) light (800—2500 nm), with these materials first applied to photodiode NIR detectors in 2007 as an alternative to more traditional inorganic devices. Although the development of organic NIR photodetectors has continued to advance, their ability to effectively detect wavelengths in the low-energy portion of the NIR spectrum is still limited. Efforts to date concerning the production of photo-diode-based devices capable of detecting light beyond 1000 nm are reviewed.

Hole-transporting materials (HTMs) are necessary for highly efficient perovskite solar cells (PSCs) to enable the hole carriers extraction and transport. There are designed varieties of HTMs so far, including small molecules and polymers. However, most of them have to be doped to get the high mobility and conductivity. Otherwise, the dopant will deteriorate the long-term stability and efficiency, which is a bottleneck for the commercialization of PSCs. The development for non-doping HTMs, which can replace the traditional doped HTMs, brings great hope to this field. Among them, acceptor (A)-donor (D)-acceptor (A) type non-doping HTMs are an important portion. In this min-review, we summarize all the A-D-A type non-doping HTMs and their properties.

The bulk-heterojunction (BHJ) polymer solar cell (PSC) has been considered as one of the most promising next-generation photovoltaic technologies. Electron-accepting material, which is the key component as important as polymer donor in the BHJ blend of a PSC, can almost only choose from fullerene derivatives before 2015. Currently, nonfullerene acceptor (NFA) materials are attracting drastically increasing interest in organic photovoltaics as alternatives for fullerene derivatives, due to their advantages of structural diversity, low-cost, as well as extraordinary chemical, thermal, and photostability. Benefiting from the facile functionalization of NFA molecules, their photoelectric properties and stacking characteristics can be adequately adjusted to promote photoinduced charge separation and extraction. In recent five years, a lot of NFA molecules have been successfully designed and synthesized, and the power conversion efficiencies of NFA-based PSCs have reached ~13%, revealing the great potential of NFA-material for improving PSCs performances. In this review, the summary and discussion are focused on the molecular architecture and device performance of three types of NFAs materials including PDI-based acceptors, A-D-A and A-π-D-π-A conjugated acceptors, aiming to understand the structure-property relationship.

The high strain cyclopropane as σ block model inserted in organic semiconductors to tune the structures and optical properties was investigated by the density functional theory method. The band gaps and absorption peaks of 1,2-disubstituted cyclopropanes were between the corresponding alkanes and olefins. The cis-isomers had higher steric strain between two substituents and lower symmetry than the trans-isomers in ground-state structures. The electronic transitions (S₀→S₁) were mainly on the aryl parts, which were stronger coherence with surrounding atoms in cis-isomers, while the trans-isomers were on the cyclopropyl. Furthermore, 1,2-disubstituted cyclopropanes (1A, 1B, 2A, 4B) could respond to the charge stimulation, which are potential materials for organic electronics and mechatronics.

Highly efficient blue phosphorescent organic light-emitting diode (OLED) is achieved by using a blend of biphenyl (spiro[fluorene-9,9'-xanthen]-2-yl) phosphine oxide (SFX2PO) and various of hole- or electron-transporting materials such as di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC), 2,2',2"-(1,3,5-benzinetriyl)-tris(1- phenyl-1-H-benzimidazole) (TPBi) and 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA). The results show that TCTA and SFX2PO can partially form exciplex and have better charge carrier balance performance. The driving voltage and efficiency are improved in a multi-player device with TCTA and SFX2PO as the co-host. The device shows a maximum current efficiency of 22.75 cd•A^–1, which is nearly two folds over the device using SFX2PO or phosphine oxide spirobifluorene derivative (SPPO1) as a single host.