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Conducting polymers with high workfunction are desirable for making ohmic contacts at electrode/organic semiconductor interfaces for electronic applications. Png et al. show workfunction up to 6 eV in hole-doped triarylamine-fluorene copolymers, explained by including electron correlation effect.

The morphology and structure of polymer blends is central to charge-carrier, exciton and photon management in organic light-emitting diodes, transistors and solar cells. A broadly applicable approach, based on mixing a photocrosslinkable moiety into semiconducting polymers, enables the simple formation of heterostructured blends with control of morphology and structure for use in all types of device.

The general photocrosslinking of semiconducting polymers is limited by efficiency and semiconductor property degradation. Here, the authors show that fluorinated phenyl azides can be molecularly designed to improve photolysis efficiency, and induce favourable partitioning of the crosslinker amongst the alkyl side chains of the polymer, thereby achieving high crosslinking efficiency without diminishing semiconducting properties.

Efficient organic light-emitting diodes require a multilayer architecture to confine charge recombination to the emissive layer. Here, authors demonstrate efficient single-layer devices for emitters with imbalanced charge transport without the need of additional charge transport or blocking layers.

Moisture sorption is a common occurrence in polyelectrolyte systems, but not yet fully understood. Here the authors, combining thermogravimetric analysis, vibrational spectroscopy, molecular force field and quantum chemical computations, provide insights into the binding of water in monovalent conjugated polyelectrolytes, establishing a model of the surface hydration of the ion clusters.

The conversion efficiency of organic solar cells depends on the shape of the interface between their donor and acceptor components. Liuet al. demonstrate a scalable method using crosslinked polymer networks to fabricate the finely interpenetrating structures needed to achieve near-perfect internal quantum efficiency.

Both open-circuit voltage and fill factor of organic solar cells are affected by the metal-organic semiconductor interface. Here, the authors demonstrate that the voltage can continue to rise when the Fermi level is forced up to the semiconductor density-of-states tail.

Realizing ultra-high work functions (UHWFs) in hole-doped polymer semiconductors remains a challenge due to water-oxidation reactions. Here, the authors determine the role of water-anion complexes in limiting the work function and develop a design strategy for realizing UHWF polymers.

The importance of ohmic contacts for organic solar cells has been recognized, but how the transition to ohmic behavior occurs is unknown. Tan et al. show that this transition happens separately beyond Fermi-level pinning, when the interfacial contact resistivity becomes sufficiently low.

Multivalent anions are found to be capable of electron-doping polymer semiconductors to realize conductive films with very low work functions, which enable efficient electron injection into materials with low electron affinity.

A modification of the elastomer stamp method enables single-layer graphene to be transferred onto virtually any arbitrary surface, including ultrathin soft polymer layers.

A general strategy for producing solution-processed doped polymers with the extreme work functions that are required to make good ohmic contacts to semiconductors is demonstrated in high-performance light-emitting diodes, transistors and solar cells.