The higher dielectric constant and electron donating properties of PTEG-1 electron extraction layer synergistically helps to eliminate the light soaking effect and enhance device performance.

We report on the fabrication of PbS-CdS (core-shell) quantum dot (QD)-sensitized solar cells by direct adsorption of core-shell QDs on mesoporous TiO 2 followed by 3-mercaptopropionic acid ligand exchange. PbS-CdS QD-sensitized solar cells show 4 times higher efficiency with respect to solar cells sensitized with PbS QDs. The significantly enhanced mean electron lifetime and electron diffusion length provide crucial evidence for the higher efficiency of the cell. The average electron lifetime increases with the thickness of the CdS shell, demonstrating that the CdS shell plays an important role in preventing carrier recombination. However, owing to the barrier provided by the offset between the conduction bands of CdS and the PbS core, the CdS shell also hinders carrier injection from PbS to TiO 2 . Herein, we studied the effect of the shell thickness on cell's performance, showing a power conversion efficiency of 1.28% for PbS QDs with a 0.5 nm CdS shell. In addition, we demonstrate that the CdS shell effectively prevents photo-corrosion of PbS, resulting in devices with highly stable photocurrent.

Here we report for the first time an H2-evolving photocathode fabricated by a solution-processed organic-inorganic hybrid composed of CdSe and P3HT. The CdSe:P3HT (10:1 (w/w)) hybrid bulk heterojunction treated with 1,2-ethanedithiol (EDT) showed efficient water reduction and hydrogen generation. A photocurrent of -1.24 mA/cm(2) at 0 V versus reversible hydrogen electrode (V(RHE)), EQE of 15%, and an unprecedented Voc of 0.85 V(RHE) under illumination of AM1.5G (100 mW/cm(2)) in mild electrolyte were observed. Time-resolved photoluminescence (TRPL), internal quantum efficiency (IQE), and transient photocurrent measurements were carried out to clarify the carrier dynamics of the hybrids. The exciton lifetime of CdSe was reduced by one order of magnitude in the hybrid blend, which is a sign of the fast charge separation upon illumination. By comparing the current magnitude of the solid-state devices and water-splitting devices made with identical active layers, we found that the interfaces of the water-splitting devices limit the device performance. The electron/hole transport properties investigated by comparing IQE spectra upon front- and back-side illumination evidenced balanced electron/hole transport. The Faradaic efficiency is 80-100% for the hybrid photocathodes with Pt catalysts and ∼70% for the one without Pt catalysts.

OPD and readout integrated circuit (ROIC) enables several advantages. [6] For example, the sensor area can potentially reach a larger fill factor as the OPD is directly overlaid on top of an ROIC, which means that more incident photons will be absorbed by the photoactive layer (PAL), leading to imagers that are more sensitive to light. [5] In addition, the response spectra for organic semiconductors can be designed and tuned by adjusting the chemical structure, and the application of organic-based image sensors can be easily extended by changing the PAL materials with various light responses. [7,8] Among image sensors, near infrared (NIR) and shortwave infrared (SWIR) imaging technologies are essential to many applications, including health monitoring, [9,10] machine vision, [11] optical communication, [12] and spectro scopy. [13] Currently, the semiconductors utilized for the detection of NIR radiation are still determined by silicon (Si) technology, [14] such that the sensor structure requires high-temperature growth and complex bonding processes, and at a cost that remains prohibitive for large-area manufacturing. The external quantum efficiencies (EQEs) of Si-based detectors are also intrinsically limited when the incident light extends to the SWIR region, in which the wavelength (λ) is longer than 1000 nm.Considering various breakthroughs during the development of OPDs, it is noted that improvements that result in high performance always rely on both material innovation and stateof-the-art device engineering. An OPD with high EQEs of 66% and 67% at a wavelength of 940 and 1000 nm has been realized recently by using a specifically designed nonfullerene acceptor (NFA). [15] This result indicates the significant future potential of organic image sensor technology. For device engineering, photo multiplication type OPD has been developed successfully for highly sensitive sensors under weak light condition. Photomultiplication effect is commonly obtained by introducing charge traps in photoactive layer of OPD to realize interfacial trap-assisted charge injection, leading to the EQE larger than 100%, and the additional amplification systems are no longer needed due to its high EQE. [16,17] Also, OPD with narrowband spectral response has also been demonstrated by introducing the photomultiplication and charge injection narrowing Near infrared (NIR) and shortwave infrared (SWIR) image technologies are of interest for many emerging applications. Among photodetector technologies, organic photodetectors (OPDs) are groundbreaking light sensors with unique photon-to-electron responses at various wavelengths that offer limitless flexibility in field applications due to the tunable design of organic semiconductors. Herein, a top-illuminated OPD deposited on bottom aluminum electrode with a spectral response beyond a wavelength of 1000 nm is reported, which suggests a feasibility for image sensors integrated with bottom readout circuit. The results reveal that a device composed of aluminum-doped zinc oxide, nickel oxide, and...

Image-sensor technology is the foundation of many emerging applications, where the photodetector is designed to interact with incoming photons that have specific colors or wavelengths. A color filter is therefore crucial to enable the selective spectral response of the photodetector and to eliminate the crosstalk interference resulting from ambient lights. Unfortunately, a reduced detection sensitivity of the photodetector is inevitable due to an imperfect light filtering, which greatly limits the practical applications of selective-response photodetectors. Herein, we demonstrate a bulk-heterojunction (BHJ) organic composite featuring a self-filtering light responsive characteristic. Through a careful optimization of the BHJ film, the organic photodetector (OPD) demonstrates a high-selective spectral response to the infrared (IR) radiation without the need of applying a color filter. As a result, the self-filtering top-illuminated OPD exhibits a narrowband external quantum efficiency (EQE) of 53% with a narrow full width at half-maximum (fwhm) of 56 nm centering at 1080 nm. A high responsivity of 0.46 A W −1 is also achieved at 1080 nm wavelength due to the self-filtering characteristic.