A blue iridium carbene complex realizes high‐efficiency blue and white OLEDs (see figure). For a blue OLED, ηp,max is recorded to be 35.9 lm W−1. For a white OLED, ηp,max and ηp,1000 are measured to be 59.9 lm W−1 and 43.3 lm W−1, respectively, without any light‐outcoupling enhancement. This white OLED also shows an illumination‐acceptable CRI over 80.

The vertical composition profile of active layer has a major effect on the performance of organic photovoltaic devices (OPVs). While stepwise deposition of different materials is a conceptually straightforward method for controlled preparation of multi-component active layers, it is practically challenging for solution processes because of dissolution of the lower layer. Herein, we overcome this difficulty by employing the photoprecursor approach, in which a soluble photoprecursor is solution-deposited then photoconverted in situ to a poorly soluble organic semiconductor. This approach enables solution-processing of the p-i-n triple-layer architecture that has been suggested to be effective in obtaining efficient OPVs. We show that, when 2,6-dithienylanthracene and a fullerene derivative PC71BM are used as donor and acceptor, respectively, the best p-i-n OPV affords a higher photovoltaic efficiency than the corresponding p-n device by 24% and bulk-heterojunction device by 67%. The photoprecursor approach is also applied to preparation of three-component p-i-n films containing another donor 2,6-bis(5′-(2-ethylhexyl)-(2,2′-bithiophen)-5-yl)anthracene in the i-layer to provide a nearly doubled efficiency as compared to the original two-component p-i-n system. These results indicate that the present approach can serve as an effective means for controlled preparation of well-performing multi-component active layers in OPVs and related organic electronic devices.

16-dione is a soluble precursor of pentacene, which can be converted into pentacene by irradiation in the solid-state. Its photoconversion process in spin-coated films was monitored by UV-visible absorption and IR spectroscopy. A small amount of high-boiling-point additives in the chloroform spin-coating solution promoted photoconversion to obtain high quality films suitable for FETs. The FET mobilities showed a correlation with the additives' boiling points and dissolution abilities, indicating that the retainment of a semidry state during photoconversion is essential to the complete photoconversion. Photoirradiation conditions (irradiation intensity, duration and substrate temperature) were optimized to achieve a field-effect mobility of 0.86 cm 2 V À1 s À1 , comparable to the performance of vacuum-deposited pentacene films. The prepared films have a partially crystalline morphology different from that of vacuum-deposited films. The high FET mobility of the photoconverted film is attributed to continuously connected grain boundaries arising from partial crystallinity.

An α-carboline derivative, 9,9′-m-phenylenedi-α-carboline (mCaP) was designed and synthesized as a host material for phosphorescent OLEDs. By using a combination with phosphorescent emitters such as FIrpic and Ir(ppy)3, we have successfully developed high-performance OLEDs with a power efficiency (ηp,100) at 100 cd m−2 of 37 lm W−1 for blue, and 94 lm W−1 for green, respectively.