Herein, we evaluated an all-inorganic perovskite based MSM photodetector employing a bilayer composite film of mp-TiO₂ and CsPbBr₃ quantum dots as a photosensitizer.

In the current work, we fabricate an all-inorganic perovskite quantum dot-based photodetector with bifunctional linker molecules, which is highly superior to its counterpart without the linker. The ultrahigh on/off ratio of 10⁵ is two orders of magnitude higher than that of the device without the ligand treatment. Moreover, the responsivity increases from ∼2.2 A W⁻¹ to ∼24.5 A W⁻¹ and the detectivity from 3.5 × 10¹² Jones to 8.9 × 10¹³ Jones. To gain further insight into the effect of ligand-exchange by bifunctional linker molecules besides surface passivation, we divide the electron transfer process into two parts, the electron transfer from quantum dots (QDs) to the linker and from the linker to TiO₂. Injection of photoexcited electrons from colloidal CsPbBr₃ QDs into TiO₂ nanoparticles by bifunctional linker molecules is found to be much faster. Continuous-wave and time-resolved fluorescence spectra exhibit strong quenching for CsPbBr₃ QDs assembled by the linker or coupled to TiO₂ nanoparticles, which is consistent with electron transfer for QDs. From the results of the transient absorption measurement and fluorescence lifetime, the electron transfer time of QDs–TiO₂ linked by the bifunctional molecules is calculated to be within 40 ns, while that from QDs to TiO₂ particles directly is estimated to be ∼290 ns. This indicates that much faster electron injection occurs under the effect of the electron linker. In addition, the linker molecule modification can improve the adsorption of mp-TiO₂ to capture more QDs.

This paper presents perovskite solar cells employed with WO₃ nanoparticles embedded carbon top electrode. WO₃ nanoparticles works as an inorganic hole-transport material (HTM) to promote the hole-extraction in the perovskite/carbon interface as revealed by efficiency, electrochemical impedance and external quantum efficiency measurements. As a result, a 40% enhancement of energy conversion efficiency has been achieved compared to the reference devices with the energy conversion efficiency of 10.77% under standard conditions. In addition, the Li-TFSI can modify the interface between electron-transport material (ETM) and perovskite, which may inhibit the recombination at the ETM/perovskite interface. The V_OC of devices upon the modification of Li-TFSI is increased from 887.9 to 934.2 mV. This work highlights about the enlightenment of the effective performance of carbon-based mesoscopic PSCs by the introduction of HTM and the modification of interfaces.

The Sn composition graded GeSn layer with Sn content increased from 11% to 14.3% was grown on a Si substrate by molecular beam epitaxy. The structural properties of the GeSn layer are investigated, and the film is gradually relaxed along the thickness, reaching approximately 71.6%. The GeSn p–i–n detectors were fabricated by using a complementary metal oxide semiconductor compatible process. The GeSn detectors demonstrated a cutoff wavelength of approximately 3.3 μm at room temperature with a dark current of 0.3 A/cm² @ -1 V. At a wavelength of 2000 nm, the GeSn detectors had a responsivity of 110 mA/W and -3 dB bandwidth (f_3 dB) about 3 GHz. These results suggest that high Sn content relax GeSn can be grown by MBE and paves the way toward the feasibility of mid-infrared GeSn photonics.

We report the design and fabrication of a high-speed GeSn normal-incidence p-i-n photodetector. To realize high-speed detection in all telecommunication bands, we optimize the Sn content in the absorption layer, the absorption-layer thickness, and the device size. The responsivity of the 18-m-diameter device at 1550 nm reaches 0.32 A/W with an extended cutoff wavelength of 1700 nm and a 3-dB bandwidth as high as 28 GHz under 3 V bias, clear open eye diagrams are also obtained under zero bias at 1630 nm. All the results indicate that the device has a significant potential for applications in Si-based optical telecommunication in all telecommunication bands.

The enhanced room-temperature photoluminescence of porous Si nanowire arrays and its mechanism are investigated. Over 4 orders of magnitude enhancement of light intensity is observed by tuning their nanostructures and surface modification. It is concluded that the localized states related to Si-O bonds and self-trapped excitations in the nanoporous structures are attributed to the strong light emission.