Highly efficient green and orange-red PhOLEDs with low efficiency roll-off enabled by a bipolar violet-blue phenanthroimidazole-based fluorophore.

Organic solar cells (OSCs) have attracted wide attention due to their economy, environmental protection, and potential for large-scale commercial production. The layer-by-layer (LbL) solution processing method, where donor solution and acceptor solution are coated sequentially, is a simple and effective way to fabricate OSCs, achieving a high power conversion efficiency (PCE) of up to 17%. Compared with bulk-heterojunction (BHJ) OSCs, LbL solution-processed OSCs separately adjust different layers, making the components distribute ideally in the vertical direction that is beneficial for exciton dissociation, charge transport, and charge collection. Moreover, the LbL approach has better potential in the preparation of large-area devices, which is a key link in the commercialization of OSCs. Herein, the basic principles and the latest research progress of LbL solution-processed OSCs are summarized, and the existing challenges and prospects of the LbL solution processing method in industrial production are discussed.

Efficient solution-processed exciplex OLEDs were developed by incorporating a novel small molecule electron-donor and utilizing the strategy of ternary exciplexes.

For comprehensive development of organic solar cells (OSCs), some factors such as environmental stability, low cost, insensitive film thickness, component contents tolerance, and green preparation processes are equally crucial to achieve high power conversion efficiencies (PCEs). In this work, a small molecule 3-(diethylamino)-7-imino-7H-benzo[4,5]imidazo[1,2-a]chromeno[3,2-c]pyridine-6-carbonitrile (DIBC), which is commercially available at low cost, is utilized to realize high-performance ternary OSCs. Demonstrated via Fourier transform infrared and 2D-1 HNMR, DIBC can form hydrogen bond interactions with [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) in solid films. Further electrostatic potential (ESP) calculations indicate that the hydrogen bond interaction enhances the ESP of PC 71 BM and accelerates charge transport between donor and acceptor. As a result, poly(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl) benzo[1,2-b;4,5-b0]dithiophene-2,6diylalt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl(PTB7-Th):DIBC:PC 71 BM-based ternary OSC achieves a maximum efficiency of 12.17%, which is the best result of green solvent processed fullerene OSCs at present. It is noteworthy that the ternary OSCs also show great tolerance to film thickness and blend ratios. These unique properties are attributed to the hydrogen-bond-linked DIBC and PC 71 BM, which modulates molecule distribution and improves film morphology with an interpenetrating network structure. Furthermore, the DIBC containing device also exhibits good thermal and light radiation stability. These results illustrate that intermolecular hydrogen bond interaction has great potential for realizing high-performance OSCs.