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A cross-linker and an elastomer are used to increase the mechanical compliance of the active layer in organic solar cells based on fullerene and non-fullerene acceptors without compromising their performance.

Top and bottom surfaces of polymer films are used to construct interfaces in heterojunction based devices, affecting device figure of merit significantly with their different aggregation states.

Solution-processed metal halide perovskite (MHP) single crystals (SCs) are in high demand for a growing number of printed electronic applications due to their superior optoelectronic properties compared to polycrystalline thin films. There is an urgent need to make SC fabrication facile, scalable, and compatible with the printed electronic manufacturing infrastructure. Here, a universal cosolvent evaporation (CSE) strategy is presented by which perovskite SCs and arrays are produced directly on substrates via printing and coating methods within minutes at room temperature from drying droplets. The CSE strategy successfully guides the supersaturation via controlled drying of droplets to suppress all crystallization pathways but one, and is shown to produce SCs of a wide variety of 3D, 2D, and mixed-cation/halide perovskites with consistency. This approach works with commonly used precursors and solvents, making it universal. Importantly, the SC consumes the precursor in the droplet, which enables the large-scale fabrication of SC arrays with minimal residue. Direct on-chip fabrication of 3D and 2D perovskite photodetector devices with outstanding performance is demonstrated. The approach shows that any MHP SC can now be manufactured on substrates using precision printing and scalable, high-throughput coating methods.

Semiconducting mesocrystalline bulk polymer specimens that exhibit near-intrinsic properties using channel-die pressing are demonstrated. A predominant edge-on orientation is obtained for poly(3-hexylthiophene-2,5-diyl) (P3HT) throughout 2 mm-thick/wide samples. This persistent mesocrystalline arrangement at macroscopic scales allows reliable evaluation of the electronic charge-transport anisotropy along all three crystallographic axes, with high mobilities found along the π-stacking. Indeed, charge-carrier mobilities of up to 2.3 cm2 V-1 s-1 are measured along the π-stack, which are some of the highest mobilities reported for polymers at low charge-carrier densities (drop-cast films display mobilities of maximum ≈10-3 cm2 V-1 s-1 ). The structural coherence also leads to an unusually well-defined photoluminescence line-shape characteristic of an H-aggregate (measured from the surface perpendicular to the materials flow), rather than the typical HJ-aggregate feature usually found for P3HT. The approach is widely applicable: to electrical conductors and materials used in n-type devices, such as poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200) where the mesocrystalline structure leads to high electron transport along the polymer backbones (≈1.3 cm2 V-1 s-1 ). This versatility and the broad applicability of channel-die pressing signifies its promise as a straightforward, readily scalable method to fabricate bulk semiconducting polymer structures at macroscopic scales with properties typically accessible only by the tedious growth of single crystals.