Herein, a simple and facile strategy is described to obtain chiroptically active semiconductor thin films by blending of poly(3-alkylthiophene)s, which are conventional achiral polymer semiconductors, and 1,1′-binaphthyl (BN), a versatile chiral molecule. As expected, the intermolecular interaction between the two materials is important to extend the chirality of the binaphthyl molecules to the hybrid films. The controlled phase separation and crystallization of poly[3-(6-carboxyhexyl)thiophene-2,5-diyl] (P3CT) and binaphthyl hybrid films result in unique heterojunction bilayer thin-film structures that consisted of BN microcrystals at the top and a P3CT/BN mixed layer at the bottom. Such heterojunction bilayer films exhibit significantly amplified chiroptical response with weak broadened tails, which is due to the enhanced crystallization of the chiral BN molecules and formation of heteroaggregates in the hybrid films. Based on the characterization of crystalline structure and photoluminescence analysis, it is found that new electronic energy states are formed in the conduction band region of P3CTs in the P3CT/BN heteroaggregates, which contribute to chirality transfer from BN to the hybrid films. As a proof of concept, a photodiode capable of distinguishably sensing the leftand right-handed circularly polarized light is successfully fabricated by using the hybrid films with the heterojunction bilayer structure.

Two-dimensional (2D) van der Waals (vdW) heterostructures herald new opportunities for conducting fundamental studies of new physical/chemical phenomena and developing diverse nanodevice applications. In particular, vdW heterojunction p−n diodes exhibit great potential as highperformance photodetectors, which play a key role in many optoelectronic applications. Here, we report on 2D MoTe 2 /MoS 2 multilayer semivertical vdW heterojunction p−n diodes and their optoelectronic application in self-powered visible−invisible multiband detection and imaging. Our MoTe 2 /MoS 2 p−n diode exhibits an excellent electrical performance with an ideality factor of less than 1.5 and a high rectification (ON/OFF) ratio of more than 10 4 . In addition, the photodiode exhibits broad spectral photodetection capability over the range from violet (405 nm) to near-infrared (1310 nm) wavelengths and a remarkable linear dynamic range of 130 dB within an optical power density range of 10 −5 to 1 W/cm 2 in the photovoltaic mode. Together with these favorable static photoresponses and electrical behaviors, very fast photo-and electrical switching behaviors are clearly observed with negligible changes at modulation frequencies greater than 100 kHz. In particular, inspired by the photoswitching results for periodic red (638 nm) and near-infrared (1310 nm) illumination at 100 kHz, we successfully demonstrate a prototype self-powered visible− invisible multiband image sensor based on the MoTe 2 /MoS 2 p−n photodiode as a pixel. Our findings can pave the way for more advanced developments in optoelectronic systems based on 2D vdW heterostructures.

Two dimensional (2D) layered van der Waals (vdW) atomic crystals are an important class of emerging materials due to their unique physical properties. In particular, the nature of dangling–bond–free surfaces in 2D vdW materials enables the formation of heterojunctions without the constraint of atomic lattice match. Here, we report on a 2D WSe2/MoS2 multilayer van der Waals heterojunction PN diode and its application for visible-near infrared broadband detection. The WSe2/MoS2 PN diode shows excellent performance with an ideality factor of 1.5 and a high rectification (ON/OFF) ratio of over 106. This PN diode exhibits spectral photo-responses from the ultraviolet (405 nm) region to the near infrared (808 nm) region with obvious photovoltaic behaviors (very clear open circuit voltage and short circuit current). In addition to the static behavior, photocurrent switching behaviors are clearly observed under periodic illuminations at up to 1 KHz. The device shows a linear response within the optical power density range of 10−5 W cm−2 to 1 W cm−2 and a linear dynamic range is estimated to be 123 dB.