Dipolar compounds for use in simplified, single‐layer organic light‐emitting devices (OLEDs) containing a dibenzothiophene S,S‐dioxide core and two peripheral diarylamines are synthesized. These materials exhibit bipolar carrier‐transport properties, and efficient single‐layer electroluminescent devices (see Figure; ITO: indium tin oxide) using these materials are demonstrated. These compounds may lead to devices with performances comparable to multilayer ones at lower costs.

A series of compounds containing arylamine and 1,2‐diphenyl‐1H‐benz[d]imidazole moieties are developed as ambipolar, blue‐emitting materials with tunable blue‐emitting wavelengths, tunable ambipolar carrier‐transport properties and tunable triplet energy gaps. These compounds possess several novel properties: (1) they emit in the blue region with high quantum yields; (2) they have high morphological stability and thermal stability; (3) they are capable of ambipolar carrier transport; (4) they possess tunable triplet energy gaps, suitable as hosts for yellow‐orange to green phosphors. The electron and hole mobilities of these compounds lie in the range of 0.68–144 × 10−6 and 0.34–147 × 10−6 cm2 V−1 s−1, respectively. High‐performance, single‐layer, blue‐emitting, fluorescent organic light‐emitting diodes (OLEDs) are achieved with these ambipolar materials. High‐performance, single‐layer, phosphorescent OLEDs with yellow‐orange to green emission are also been demonstrated using these ambipolar materials, which have different triplet energy gaps as the host for yellow‐orange‐emitting to green‐emitting iridium complexes. When these ambipolar, blue‐emitting materials are lightly doped with a yellow‐orange‐emitting iridium complex, white organic light‐emitting diodes (WOLEDs) can be achieved, as well by the use of the incomplete energy transfer between the host and the dopant.

Semitransparent organic photovoltaics (ST‐OPVs) have great potential for use in renewable energy technologies. In bulk‐heterojunction (BHJ) ST‐OPVs, a compromise is necessary between the visible light transmittance (VLT) and the power conversion efficiency (PCE). A sequential deposition (SD) strategy that involves individually depositing a polymer donor layer (D) and a small‐molecule acceptor layer (A) as the active layer is presented; where molecular diffusion occurring at the interfacial region results in a pseudo p–i–n structure. PBDB‐T‐2F(D)/Y6(A) ST‐OPVs are fabricated with different active layer thicknesses—at 115 nm, the SD (D:A/75:40 nm) and BHJ devices (D:A/1:1.2 w) provide the champion PCE of 12.91% (VLT of 14.5%) and 12.77% (VLT of 13.4%), respectively; at 85 nm, the SD (D:A/45:40 nm) and BHJ devices (D:A/1:1.2 w) provide a PCE of 12.22% (VLT of 22.2%) and 11.23% (VLT of 16.6%), respectively. This trend indicates SD devices have larger PCE and VLT values than the BHJ devices at a given active layer thickness, and the enhancements of PCE and VLT values by the SD structures against the BHJ structures become more pronounced as the active layer thickness reduced. The SD strategy provides a new approach for achieving ST‐OPVs with both high efficiency and high transparency.

Organic light-emitting diodes (OLEDs) have attracted a great deal of interest because of their potential applications in full-color flat-panel displays and lighting sources.[1] Considerable progress has been made on both small-molecule-and polymer-based OLEDs. Though blue-, green-, and redemitting materials are all needed for OLED applications, currently development of deep-blue emitters with good stability and high luminescence efficiency is deemed most critical in effectively reducing the power consumption and generating emission of different colors (including white light). In recent years considerable efforts have been shifted to the development of luminescent transition-metal complexes, particularly second-and third-row transition metals.[2] As a result of efficient spin-orbit coupling in these complexes, both singlet and triplet excitons can be harvested, and theoretically up to 100 % internal quantum efficiencies can be attained. However, metal complexes are typically crystalline and must be used as a dopant in an appropriate host. Furthermore, the host and materials used for carrier transport or carrier blocking must have sufficiently large triplet (T 1 ) energy to prevent the loss of triplet excitons from the metal complexes.[3] Therefore, phosphorescence-based devices frequently have complicated structures. Since blue-emitting phosphorescent materials have relatively a large triplet energy, it becomes increasingly difficult to find host materials with a suitably high triplet state.