An optical switch with two distinct resonances is formed by combining PbS nanocrystals and the conductive polymer poly[sodium 2-(2-ethynyl-4-methoxyphenoxy)acetate] (PAE) into a hybrid thin film. Infrared excitation of the nanocrystals invokes charge transfer and consecutive polaron formation in the PAE, which activates the switch for excited-state absorption at visible frequencies. The optical modulation of the photocurrent response of the switch exhibits highly wavelength-selective ON/OFF ratios. Transient absorption spectroscopy shows that the polaron formation is correlated with the excited state of the nanocrystals, opening up new perspectives for photonic data processing. Such correlated activated absorption can be exploited to enhance the sensitivity for one optical signal by a second light source of different frequency as part of an optical amplifier or a device with AND logic.

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We functionalize PbS nanocrystals with the organic semiconductor Zn β-tetraaminophthalocyanine to design a nanostructured solid-state material with frequent organic–inorganic interfaces. By transient absorption and fluorescence spectroscopy, we investigate the optoelectronic response of this hybrid material under near-infrared excitation to find efficient charge transfer from the nanocrystals to the molecules. We demonstrate that the material undergoes cooperative sensitization of two nanocrystals followed by photon upconversion and singlet emission of the organic semiconductor. The upconversion efficiency resembles that of comparable systems in solution, which we attribute to the large amount of interfaces present in this solid-state film. We anticipate that this synthetic strategy has great prospects for increasing the open-circuit voltage in PbS nanocrystal-based solar cells.@en

We simultaneously surface-functionalize PbS nanocrystals with Cu 4,4′,4′′,4′′′-tetraaminophthalocyanine and assemble this hybrid material into macroscopic monolayers. Electron microscopy and X-ray scattering reveal a granular mesocrystalline structure with strong coherence between the atomic lattice and the superlattice of nanocrystals within each domain. Terahertz spectroscopy and field-effect transistor measurements indicate efficient coupling of holes throughout the hybrid thin film, in conjunction with a pronounced photoresponse. We demonstrate the potential of this material for optoelectronic applications by fabricating a light-effect transistor.

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