Solar cells made of lead perovskite crystals have attracted much attention for their high performance, but far less attention as a subject of crystal engineering. Here, we report that citric acid (CA) and chloride anion, working together, modulate crystal growth of CHNHPbI, producing sub-mm-sized cuboid crystals-a morphology more suitable for close packing in a thin film than the commonly observed elongated dodecahedral morphology. By using a 15 wt % CA-doped precursor solution, we formed a single layer of large, flat, and oriented cuboid crystals with minimum crystal domain boundaries and maximum contact with neighboring layers, and fabricated an archetypal inverted-structured device of 4 mm area, which showed, reproducibly and with little hysteresis, 16.75% power conversion efficiency (PCE), 26% higher than the PCE obtained for a polycrystalline film made without CA doping. Under weaker irradiation of a 1 cm device, the PCE improved from 14.52% (one sun) to 20.4% (0.087 suns). Under illumination with white light emitting diode, a 10 wt % CA-doped device showed PCE of 28.1%, suggesting an advantage of PVK-SCs for indoor applications. Further studies on crystal growth modulation will be beneficial for manufacturing efficient and stable lead perovskite solar cells.

Spiro-conjugated systems are attracting considerable interest for their chiroptical properties and because of their compact structure the small reorganization energy upon electronic excitation or ionization. We report here a modular and convergent synthesis of axially chiral spiro-conjugated carbon-bridged p-phenylenevinylenes (spiro-CPVs) in a racemic and optically active form where two carbon-bridged p-phenylenevinylene molecules are connected by a spiro carbon atom. Our synthetic design focuses on the C 2 symmetry of the spiro-CPV molecules, relying on coupling of two 3-lithio-2-arylindene molecules on a carbon monooxide molecule that serves as the spiro carbon center in the target molecule. We prepared derivatives including those possessing phenol groups that facilitate optical resolution and also serve as a platform for the synthesis of a variety of optically active derivatives, which exhibit circularly polarized photoluminescence with high fluorescence quantum yields, large dissymmetry factors, and high photostability. For example, a bis­(phenylethynyl) derivative exhibited a fluorescence quantum yield of 0.99 and a dissymmetry factor in luminescence of |g lum| = 2.7 × 10–4, values highest among and comparable to those of reported CPL compounds, respectively. A tetrakis-diarylamine derivative shows hole mobility (μh = 3.84 × 10–5 cm2 V–1 s–1; space charge-limited current measurement of a spin-coated film) comparable to that of a popularly used hole-transporting material, spiro-OMeTAD (μh = 2.6 × 10–5 cm2 V–1 s–1), as well as high thermal and phase stability (T 5d = 382 °C, T g = 171 °C).

A series of acridinium salts with high excited-state oxidative power are employed as photoredox organocatalysts in conjunction with various thioesters, such as trithiocarbonate, dithiocarbamate, and xanthate, and thioacetals for photomediated...

A n i r o n ( I I I ) s a l t , ( Z ) -1 , 2 -b i s -(diphenylphosphino)ethene or its electron-rich congener, (Z)-1,2-bis[bis(4-methoxyphenyl)phosphine]ethene, and a zinc(II) salt catalyze the arylation, heteroarylation, and alkenylation of propionamides possessing an 8-quinolylamide group with organoborate reagents in the presence of 1,2-dichlorobutane as oxidant at 70 °C. Stoichiometric experiments provided evidence for the involvement of an organoiron(III) species as a key intermediate for C−H activation and C−C bond formation.

The oxygenation of C(sp3)–H bonds is a key chemical reaction in the production of fine chemicals and pharmaceuticals. Hydrogen atom transfer has recently gained significant attention for its ability to...