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SUMMARYThe circadian clock control of CONSTANS (CO) transcription and the light-mediated stabilization of its encoded protein coordinately adjust photoperiodic flowering by triggering rhythmic expression of the floral integrator flowering locus T (FT). Diurnal accumulation of CO is modulated sequentially by distinct E3 ubiquitin ligases, allowing peak CO to occur in the late afternoon under long days. Here we show that CO abundance is not simply targeted by E3 enzymes but is also actively self-adjusted through dynamic interactions between two CO isoforms. Alternative splicing of CO produces two protein variants, the full-size COa and the truncated COb lacking DNA-binding affinity. Notably, COb, which is resistant to E3 enzymes, induces the interaction of COa with CO-destabilizing E3 enzymes but inhibits the association of COa with CO-stabilizing E3 ligase. These observations demonstrate that CO plays an active role in sustaining its diurnal accumulation dynamics during Arabidopsis photoperiodic flowering.

Intrinsically stretchable organic light‐emitting diodes (ISOLEDs) are becoming essential components of wearable electronics. However, the efficiencies of ISOLEDs have been highly inferior compared with their rigid counterparts, which is due to the lack of ideal stretchable electrode materials that can overcome the poor charge injection at 1D metallic nanowire/organic interfaces. Herein, highly efficient ISOLEDs that use graphene‐based 2D‐contact stretchable electrodes (TCSEs) that incorporate a graphene layer on top of embedded metallic nanowires are demonstrated. The graphene layer modifies the work function, promotes charge spreading, and impedes inward diffusion of oxygen and moisture. The work function (WF) of 3.57 eV is achieved by forming a strong interfacial dipole after deposition of a newly designed conjugated polyelectrolyte with crown ether and anionic sulfonate groups on TCSE; this is the lowest value ever reported among ISOLEDs, which overcomes the existing problem of very poor electron injection in ISOLEDs. Subsequent pressure‐controlled lamination yields a highly efficient fluorescent ISOLED with an unprecedently high current efficiency of 20.3 cd A−1, which even exceeds that of an otherwise‐identical rigid counterpart. Lastly, a 3 inch five‐by‐five passive matrix ISOLED is demonstrated using convex stretching. This work can provide a rational protocol for designing intrinsically stretchable high‐efficiency optoelectronic devices with favorable interfacial electronic structures.

MXenes constitute a rapidly growing family of 2D materials that are promising for optoelectronic applications because of numerous attractive properties, including high electrical conductivity. However, the most widely used titanium carbide (Ti3C2Tx) MXene transparent conductive electrode exhibits insufficient environmental stability and work function (WF), which impede practical applications Ti3C2Tx electrodes in solution‐processed optoelectronics. Herein, Ti3C2Tx MXene film with a compact structure and a perfluorosulfonic acid (PFSA) barrier layer is presented as a promising electrode for organic light‐emitting diodes (OLEDs). The electrode shows excellent environmental stability, high WF of 5.84 eV, and low sheet resistance RS of 97.4 Ω sq−1. The compact Ti3C2Tx structure after thermal annealing resists intercalation of moisture and environmental contaminants. In addition, the PFSA surface modification passivates interflake defects and modulates the WF. Thus, changes in the WF and RS are negligible even after 22 days of exposure to ambient air. The Ti3C2Tx MXene is applied for large‐area, 10 × 10 passive matrix flexible OLEDs on substrates measuring 6 × 6 cm. This work provides a simple but efficient strategy to overcome both the limited environmental stability and low WF of MXene electrodes for solution‐processable optoelectronics.