Highly efficient and bendable organic solar cells (OSCs) are fabricated using solution‐processed silver nanowire (Ag NW) electrodes. The Ag NW films were highly transparent (diffusive transmittance ≈ 95% at a wavelength of 550 nm), highly conductive (sheet resistance ≈ 10 Ω sq−1), and highly flexible (change in resistance ≈ 1.1 ± 1% at a bending radius of ≈200 μm). Power conversion efficiencies of ≈5.80 and 5.02% were obtained for devices fabricated on Ag NWs/glass and Ag NWs/poly(ethylene terephthalate) (PET), respectively. Moreover, the bendable devices fabricated using the Ag NWs/PET films decrease slightly in their efficiency (to ≈96% of the initial value) even after the devices had been bent 1000 times with a radius of ≈1.5 mm.

The work function and surface property of ZnO can be simply tuned by the self-assembled monolayer (SAM) molecules derived from benzoic acid such as 4-methoxybenzoic acid (MBA), 4-tert-butylbenzoic acid (BBA), and 4-fluorobenzoic acid (FBA), which have different dipole orientation and magnitude. MBA, BBA, and FBA treated ZnO layers were used as an electron injection/transporting layer for inverted type polymer solar cells (PSCs) with a structure of ITO/SAM treated ZnO/active layer (P3HT:PC61BM)/MoO3/Ag. The power conversion efficiency (PCE) of PSCs based on MBA and BBA treated ZnO reaches 3.34 and 2.94%, respectively, while the PCE of the device based on untreated ZnO is 2.47%. In contrary, the PCE of the device with FBA treated ZnO is 1.81%. The open circuit voltage (V oc) of the device with MBA, BBA, and FBA treated ZnO is 0.63 and 0.62 V, respectively, while the V oc of PSC with untreated ZnO is 0.60 V. Contrarily, the V oc of the device with FBA treated ZnO is 0.53 V. The PCE and V oc of PSCs based on MBA and BBA treated ZnO are better than those of the other devices. This seems to be related with the direction of dipole moment of benzoic acid derivatives. Also, the morphology of the active layer seems to be affected by the substituent on the 4-position of benzoic acid. The active layer on MBA treated ZnO shows optimized morphology, and its device shows the best performances. We demonstrate that the work function and morphology of the active layer can be controlled by SAM treatment of the ZnO surface with different dipole orientation and a substituent on the 4-position of benzoic acid. These are very simple and effective methods for improving the performances of PSCs. The results provide an alternative strategy to improve the interface property between inorganic and organic materials in organic electronic devices.

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Stretchable organic light-emitting diodes are ubiquitous in the rapidly developing wearable display technology. However, low efficiency and poor mechanical stability inhibit their commercial applications owing to the restrictions generated by strain. Here, we demonstrate the exceptional performance of a transparent (molybdenum-trioxide/gold/molybdenum-trioxide) electrode for buckled, twistable, and geometrically stretchable organic light-emitting diodes under 2-dimensional random area strain with invariant color coordinates. The devices are fabricated on a thin optical-adhesive/elastomer with a small mechanical bending strain and water-proofed by optical-adhesive encapsulation in a sandwiched structure. The heat dissipation mechanism of the thin optical-adhesive substrate, thin elastomer-based devices or silicon dioxide nanoparticles reduces triplet-triplet annihilation, providing consistent performance at high exciton density, compared with thick elastomer and a glass substrate. The performance is enhanced by the nanoparticles in the optical-adhesive for light out-coupling and improved heat dissipation. A high current efficiency of ~82.4 cd/A and an external quantum efficiency of ~22.3% are achieved with minimum efficiency roll-off.