Effect of Temperature on Photovoltaic Solar Cell Cadmium Telluride Thin Film

Solar cell technology comes with unique temperature coefficients. These temperature coefficients are important and temperature of the solar cell has direct influence on the power output of a photovoltaic cells. CdTe is a very robust and chemically stable material and for this reason its related solar cell. Thin film photovoltaic technology is now the only thin film technology in the first top 10 producers in the world. The strong improvement in efficiency in the last 7 years was obtained by a new redesign of the CdTe solar cell device reaching a single solar cell. In this paper, we describe the fabrication process following the history of the solar cell as it was developed in the early years up to the latest development and changes. The configuration of fabricated cell is n-CdTe/NaOH (0.15 M) + S (0.15 M) + Na2S (0.15 M)/C(graphite). The junction ideality factor was found to be 2.63, 2.13, and 1.89. The flat band potential is found to be -0.400, -0.450, -0.501 V. The barrier height value was found to be 0.523, 0.487, and 0.436 eV. The study of power output characteristic shows open circuit voltage, short circuit current, fill factor and efficiency were found to be 120 mV, 24.2 μA, 32.68%, 26.18%, and 19.73% and 0.63%, 0.37%, and 0.23%, respectively. The lighted ideality factor was calculated and found to be 3.26, 1.87, and 1.17. Spectra attain maximum value of current at λ = 580 nm and decrease with increase in wavelength. The photovoltaic cell characterization of the thin films is carried out by studying current-voltage characteristics in dark, capacitance-voltage in dark, barrier height measurements, power output characteristics.

Ultra-thin vertical tft photosensor and photosynapse based on au-doped-graphene under transition metal selenide reaction

The development of artificial photosensitive synapses with high sensitivity and biomimetic properties that combine innovative concepts and neuromorphic architectures is crucial to achieving highly integrated and flexible intelligent visual systems.Recently,graphene heterostructure-based photosensitive synaptic transistors have been extensively studied for this purpose.However,compared to traditional transistors,vertical structure thin film transistors(VTFTs)with ultra-short channels and advantages,such as high integration,have yet to be investigated in photosensitive synapses.Here,we report an ultra-thin VTFT featuring a graphene/W_(x)Se_(x-1)van der Waals heterostructure that combines photonic and neuromorphic elements.We demonstrate a VTFT in which the channel layer is formed by covalently bonded W_(x)Se_(x-1)nanomaterials produced by introducing Se atoms on the surface of a tungsten metal thin film deposited via radio-frequency sputtering.This structure successfully simulated the main synaptic function,exhib-ited photosensitive synaptic responses to ultraviolet(λ=365 nm)light,and demonstrated highly reliable electrical performance.Furthermore,the incorporation of gold nanoparticles changed the photosensitive synaptic response properties of the graphene/W_(x)Se_(x-1)heterostructure from excitatory to inhibitory,show-ing a responsivity of about∼14 A W-1,which was attributed to the heterojunction interface resonant effects and efficient charge transfer induced by localized surface plasmons.This further enabled optical artificial synaptic applications while operating with low voltage spikes and low light intensity.This work provides a novel strategy for integrating and developing biological and nano-electronic systems.

Highly responsive biosensors based on organic field-effect transistors under light irradiation

High responsivity and sensitivity play essential roles in the development of organic field-effect transistors(OFETs)-based biosensors with regard to biological detections,particularly for disease diagnosis.Nonetheless,how to design a biosensor which improves these two outstanding properties while achieving low cost,easy processing,and time saving is a daunting challenge.Herein,a novel biosensor based on OFET with copolymer thin film,whose surface is illuminated with a suitable light beam is reported.This film can be used as both an organic semiconductor material and as a photoelectric active material.Due to amplification of signals as a result of the film’s strong response to light,the biosensor possesses higher responsivity and sensitivity compared to dark condition and even realizes a maximum responsivity of up to 10^(3)for alpha-fetoprotein(AFP)detection.The simple combination of light and transistor builds a bridge between photoelectric effect and biological system.In addition,the emergence of more excellent photoelectric active materials is expected to pave a way for ultrasensitive bio-chemical diagnostic tools.

A p-silicon nanowire/n-ZnO thin film heterojunction diode prepared by thermal evaporation

This paper represents the electrical and optical characteristics of a SiNW/ZnO heterojunction diode and subsequent studies on the photodetection properties of the diode in the ultraviolet （UV） wavelength region. In this work, silicon nanowire arrays were prepared on p-type （100）-oriented Si substrate by an electroless metal deposition and etching method with the help of ultrasonication. After that, catalyst-free deposition of zinc oxide （ZnO） nanowires on a silicon nanowire （SiNW） array substrate was done by utilizing a simple and cost-effective thermal evaporation technique without using a buffer layer. The SEM and XRD techniques are used to show the quality of the as-grown ZnO nanowire film. The junction properties of the diode are evaluated by measuring current-voltage and capacitance-voltage characteristics. The diode has a well-defined rectifying behavior with a rectification ratio of 190 at -t-2 V, turn-on voltage of 0.5 V, and barrier height is 0.727 eV at room temperature under dark conditions. The photodetection parameters of the diode are investigated in the bias voltage range of ± 2 V. The diode shows responsivity of 0.8 A/W at a bias voltage of 2 V under UV illumination （wavelength = 365 nm）. The characteristics of the device indicate that it can be used for UV detection applications in nano-optoelectronic and photonic devices.