We present the efficient synthesis and photovoltaic response of a linearly conjugated molecule DT-DPP (AAnAT)₂, which contains a dithienyldiketopyrrolopyrrole core symmetrically connected through a 9,10-anthracenyl unit to 3-alkylthiophene via an acetylene linkage. The compound is crystalline with a T_m of 204 °C. The as-cast film has a main broad absorption at 650 nm with a shoulder at 737 nm, tailing until ca. 800 nm. The HOMO level was estimated as −5.26 eV, derived from the first reversible electron oxidation wave at ca. 0.93 V vs. Ag/AgCl reference electrode. The space charge limited current hole mobility of a pristine film is ca. 2.90×10⁻⁴ cm² V⁻¹ s⁻¹. The preliminary characterization of simple bulk heterojunction solar cells provides a power conversion efficiency (PCE) of ca. 4.0 % with V_OC=0.77 V, J_SC=10.0 mA cm⁻², and FF=52 %, based on the as-cast active layer without a processing additive or solvent vapor annealing. Thermal annealing the active layer at a mild temperature of 50 °C increased the PCE to 4.39 % due mainly to the improvement of the FF.

Cathode interfacial material (CIM) is critical to improving the power conversion efficiency (PCE) and long-term stability of an organic photovoltaic cell that utilizes a high work function cathode. In this contribution, a novel CIM is reported through an effective and yet simple combination of triarylphosphine oxide with a 1,10-phenanthrolinyl unit. The resulting CIM possesses easy synthesis and purification, a high T _g of 116 °C and attractive electron-transport properties. The characterization of photovoltaic devices involving Ag or Al cathodes shows that this thermally deposited interlayer can considerably improve the PCE, due largely to a simultaneous increase in V _oc and FF relative to the reference devices without a CIM. Notably, a PCE of 7.51% is obtained for the CIM/Ag device utilizing the active layer PTB7:PC₇₁BM, which far exceeds that of the reference Ag device and compares well to that of the Ca/Al device. The PCE is further increased to 8.56% for the CIM/Al device (with J _sc = 16.81 mA cm⁻², V _oc = 0.75 V, FF = 0.68). Ultraviolet photoemission spectroscopy studies reveal that this promising CIM can significantly lower the work function of the Ag metal as well as ITO and HOPG, and facilitate electron extraction in OPV devices.

A new series of monoammonium-based organic electrolytes with the tetrafluoroborate (BF₄⁻) counteranion have been synthesized. Replacing the pendant ethyl groups in the fluorenyl unit with 4-ethoxyphenyl groups dramatically improves both solubility and morphological stability. The characterization of the alcohol-processable amorphous ionic compounds as an electron-injection layer in organic light-emitting diodes (OLEDs) reveals that the organic electrolyte that comprises a rigid linear-conjugated unit provides better device performance, with respect to its counterpart containing a branched bulky moiety. The capability of these compounds to facilitate electron injection from air-stable aluminum metal is preliminarily discussed on the basis of the investigations of the electron-only devices and photovoltaic experiments.

Soluble molecular red emitters 1a/1b are synthesized by Stille coupling from 2-(3,5-di(1-naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610 nm in CH₂Cl₂ solution and 620 nm in solid films. Replacing the n-hexyl substituent by 4-sec-butoxyphenyl produces a marked increase of glass transition temperature (T_g) from 82 °C to 137 °C and increases the solubility in toluene and p-xylene, thus improving the film-forming properties. Cyclic voltammetry shows that the compounds can be reversibly oxidized and reduced around +1.10 and −1.20 V, respectively. A two-layered electroluminescent device based on 1b produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1 cd A⁻¹. Furthermore, when used as a solution-processed red emitter in optically pumped laser devices, compound 1b successfully produces a lasing emission at ca. 650 nm.