Ultra-optical characterization of thin film solar cells materials using core/shell absorber layer

<span>This paper investigates on new design of heterojunction quantum dot (HJQD) photovoltaics solar cells CdS/PbS that is based on quantum dot metallics PbS core/shell absorber layer and quantum dot window layer. It has been enhanced the performance of traditional HJQD thin film solar cells model based on quantum dot absorber layer and bulk window layer. The new design has been used sub-micro absorber layer thickness to achieve high efficiency with material reduction, low cost, and time. Metallics-semiconductor core/shell absorber layer has been succeeded for improving the optical characteristics such energy band gap and the absorption of absorber layer materials, also enhancing the performance of HJQD ITO/CdS/QDPbS/Au, sub micro thin film solar cells. Finally, it has been formulating the quantum dot (QD) metallic cores concentration effect on the absorption, energy band gap and electron-hole generation rate in absorber layers, external quantum efficiency, energy conversion efficiency, fill factor of the innovative design of HJQD cells.</span>

Metal oxide charge transfer complex for effective energy band tailoring in multilayer optoelectronics

Metal oxides are intensively used for multilayered optoelectronic devices such as organic light-emitting diodes (OLEDs). Many approaches have been explored to improve device performance by engineering electrical properties. However, conventional methods cannot enable both energy level manipulation and conductivity enhancement for achieving optimum energy band configurations. Here, we introduce a metal oxide charge transfer complex (NiO:MoO3-complex), which is composed of few-nm-size MoO3 domains embedded in NiO matrices, as a highly tunable carrier injection material. Charge transfer at the finely dispersed interfaces of NiO and MoO3 throughout the entire film enables effective energy level modulation over a wide work function range of 4.47 – 6.34 eV along with enhanced electrical conductivity. The high performance of NiO:MoO3-complex is confirmed by achieving 189% improved current efficiency compared to that of MoO3-based green OLEDs and also an external quantum efficiency of 17% when applied to blue OLEDs, which is superior to 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile-based conventional devices.

p-Type Iodine-Doping of Cu3N and Its Conversion to γ-CuI for the Fabrication of γ-CuI/Cu3N p-n Heterojunctions

Cu3N with a cubic crystal structure is obtained in this paper by the sputtering of Cu under N2 followed by annealing under NH3: H2 at 400 °C, after which it was doped with iodine at room temperature resulting into p-type Cu3N with hole densities between 1016 and 1017 cm−3. The Cu3N exhibited distinct maxima in differential transmission at ~2.01 eV and 1.87 eV as shown by ultrafast pump-probe spectroscopy, corresponding to the M and R direct energy band gaps in excellent agreement with density functional theory calculations, suggesting that the band gap is clean and free of mid-gap states. The Cu3N was gradually converted into optically transparent γ-CuI that had a hole density of 4 × 1017 cm−3, mobility of 12 cm2/Vs and room temperature photoluminescence at 3.1 eV corresponding to its direct energy band gap. We describe the fabrication and properties of γ-CuI/TiO2/Cu3N and γ-CuI/Cu3N p-n heterojunctions that exhibited rectifying current-voltage characteristics, but no photogenerated current attributed to indirect recombination via shallow states in Cu3N and/or deep states in the γ-CuI consistent with the short (ps) lifetimes of the photoexcited electrons-holes determined from transient absorption–transmission spectroscopy.

Enhancing CO2 photoreduction over ZIF-based reticular materials by morphology control of Au plasmonic nanoparticles

Zeolitic imidazolate frameworks (ZIFs) are promising photocatalysts for CO2 reduction due to their proper energy band structure and crystalline properties. However, CO2 conversion is still low due to the serious...

Influence of pH-Neutral Lithium Polystyrenesulfonate Polyelectrolyte on the Energy Band Structure and Performance of Organic Solar Cells

Poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) is used ubiquitously in organic solar cells (OSCs) devices, however, it is not clear how the anionic PSS component by itself affects the band structure...

A highly enhanced photoelectrochemical performance of BiVO4 photoanodes modified with CoPi groups by increasing energy band bending, accelerating hole separation and improving water oxidation kinetics

BiVO4 is one of the most attractive photoanode materials for photoelectrochemical water splitting. Herein, cobalt phosphate (CoPi) modified BiVO4 (BiVO4/CoPi) photoanode is prepared by electrodeposition. The physical and chemical characterization...

Tailoring the Energy Harvesting Capacity of Zinc Selenide Semiconductor Nanomaterial through Optical Band Gap Modeling Using Genetically Optimized Intelligent Method

Zinc selenide (ZnSe) nanomaterial is a binary semiconducting material with unique features, such as high chemical stability, high photosensitivity, low cost, great excitation binding energy, non-toxicity, and a tunable direct wide band gap. These characteristics contribute significantly to its wide usage as sensors, optical filters, photo-catalysts, optical recording materials, and photovoltaics, among others. The light energy harvesting capacity of this material can be enhanced and tailored to meet the required application demand through band gap tuning with compositional modulation, which influences the nano-structural size, as well as the crystal distortion of the semiconductor. This present work provides novel ways whereby the wide energy band gap of zinc selenide can be effectively modulated and tuned for light energy harvesting capacity enhancement by hybridizing a support vector regression algorithm (SVR) with a genetic algorithm (GA) for parameter combinatory optimization. The effectiveness of the SVR-GA model is compared with the stepwise regression (SPR)-based model using several performance evaluation metrics. The developed SVR-GA model outperforms the SPR model using the root mean square error metric, with a performance improvement of 33.68%, while a similar performance superiority is demonstrated by the SVR-GA model over the SPR using other performance metrics. The intelligent zinc selenide energy band gap modulation proposed in this work will facilitate the fabrication of zinc selenide-based sensors with enhanced light energy harvesting capacity at a reduced cost, with the circumvention of experimental stress.