A significant challenge in the rational design of organic thermoelectric materials is to realize simultaneously high electrical conductivity and high induced-voltage in response to a thermal gradient, which is represented by the Seebeck coefficient. Conventional wisdom posits that the polymer alone dictates thermoelectric efficiency. Herein, we show that doping — in particular, clustering of dopants within conjugated polymer films — has a profound and predictable influence on their thermoelectric properties. We correlate Seebeck coefficient and electrical conductivity of iodine-doped poly(3-hexylthiophene) and poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2′;5′,2′′;5′′,2′′′-quaterthiophen-5,5′′′-diyl)] films with Kelvin probe force microscopy to highlight the role of the spatial distribution of dopants in determining overall charge transport. We fit the experimental data to a phonon-assisted hopping model and found that the distribution of dopants alters the distribution of the density of states and the Kang–Snyder transport parameter. These results highlight the importance of controlling dopant distribution within conjugated polymer films for thermoelectric and other electronic applications.

Herein we demonstrate that efficient perovskite solar cells can be fabricated by a desktop multi-channel inkjet printer. In this approach, different alkyl-ammonium counterions were loaded separately into the printer cartridges and deposited onto PbI 2 coated substrates. Structural as well as electronic properties of perovskite solar cells can be tuned by varying the composition ratio of multiple cations in-situ through the RGB color codes of the multi-channel inkjet printer. This roll-to-roll compatible technique provides rapid and facile screening of multiple and mixed counterion perovskite solar cell systems with high reproducibility, potentially leading to possibilities of high-throughput screening technique in future perovskite solar cell fabrication.

Using impedance spectroscopy and computation, we show that incorporation of multiwall carbon nanotubes (MWCNTs) in the bulk of the active layer of perovskite-based solar cells reduces charge recombination and increases the open circuit voltage. An ~87% reduction in recombination was achieved when MWCNTs were introduced in the planar-heterostructure perovskite solar cell containing mixed counterions. The open circuit voltage (V oc) of perovskite/MWCNTs devices was increased by 70 mV, while the short circuit current density (J sc) and fill factor (FF) remained unchanged.

Binding behaviors of streptavidin were investigated with different lateral packing densities of biotin-functionalized, non-biofouling pOEGMA brushes, synthesized by surface-initiated polymerization from mixed SAMs with different mole fractions of the polymerization initiator on gold surfaces.