No description available.

Prepared for the United States, Department of Energy, under contract no. EX-76-A-01-2295, task order 37, by Energy Laboratory, Massachusetts Institute of Technology.

No description available.

No description available.

Electroluminescence (EL) imaging is a fast and comparatively low-cost method for spatially resolved analysis of photovoltaic (PV) devices. A Silicon CCD or InGaAs camera is used to capture the near infrared radiation, emitted from a forward biased PV device. EL images can be used to identify defects, like cracks and shunts but also to map physical parameters, like series resistance. The lack of suitable image processing routines often prevents automated and setup-independent quantitative analysis. This thesis provides a tool-set, rather than a specific solution to address this problem. Comprehensive and novel procedures to calibrate imaging systems, to evaluate image quality, to normalize images and to extract features are presented. For image quality measurement the signal-to-noise ratio (SNR) is obtained from a set of EL images. Its spatial average depends on the size of the background area within the EL image. In this work the SNR will be calculated spatially resolved and as (background independent) averaged parameter using only one EL image and no additional information of the imaging system. This thesis presents additional methods to measure image sharpness spatially resolved and introduces a new parameter to describe resolvable object size. This allows equalising images of different resolutions and of different sharpness allowing artefact-free comparison. The flat field image scales the emitted EL signal to the detected image intensity. It is often measured through imaging a homogeneous light source such as a red LCD screen in close distance to the camera lens. This measurement however only partially removes vignetting the main contributor to the flat field. This work quantifies the vignetting correction quality and introduces more sophisticated vignetting measurement methods. Especially outdoor EL imaging often includes perspective distortion of the measured PV device. This thesis presents methods to automatically detect and correct for this distortion. This also includes intensity correction due to different irradiance angles. Single-time-effects and hot pixels are image artefacts that can impair the EL image quality. They can conceivably be confused with cell defects. Their detection and removal is described in this thesis. The methods presented enable direct pixel-by-pixel comparison for EL images of the same device taken at different measurement and exposure times, even if imaged by different contractors. EL statistics correlating cell intensity to crack length and PV performance parameters are extracted from EL and dark I-V curves. This allows for spatially resolved performance measurement without the need for laborious flash tests to measure the light I-V- curve. This work aims to convince the EL community of certain calibration- and imaging routines, which will allow setup independent, automatable, standardised and therefore comparable results. Recognizing the benefits of EL imaging for quality control and failure detection, this work paves the way towards cheaper and more reliable PV generation. The code used in this work is made available to public as library and interactive graphical application for scientific image processing.

This thesis describes the development and characterisation of dye sensitised Inorganic:Organic (10) heterojunction photovoltaic (PV) cells of the form Au/MPc/TiO2/InSnO2 or F-SnO2 (where MPc= copper phthalocyanine, chloroaluminium phthalocyanine or lead phthalocyanine). The transparent TiO2 films were prepared by Sol-Gel techniques and characterised optically, structurally and electrically. The effects of and interactions between Sol-Gel process parameters have shown that the parameters undergo significant interaction with particular effects on the TiO2 film thickness and thickness related properties obtained during dip coating. The film refractive index n was in the range 2.73-1.81 and wavelength dependent. The conductivity of the films derived from Au/TiO2/InSnO2 structure was 4.26x10[-6]S/cm. E[0] varied from 3.4-3.35eV where delta=2 indicting an indirect allowed transition in 1 layer thick films to E[0] ~3.2eV where delta=3 indicating indirect forbidden transition as the number of coating layers increased. The spectral response, dark and illuminated J(V) and dark C(V) characteristics of the dye sensitised 10 PV cells have been determined. Spectral response indicates that all of the organic dyes studied can be used to sensitise Sol-Gel derived TiO2 into the visible region Corresponding photovoltaic and junction parameters were derived. Photovoltaic effects were observed in all devices studied, however cell efficiencies were poor, in the range (eta~0.0001-0.046%). The low quantum efficiencies were anticipated to be a consequence of the presence of recombination centres at the TiO2/MPc heterointerfaces and the high observed series resistance due to the low conductivity of the MPc films. The MPc/TiO2 junction formed a rectifying contact. C(V) analysis indicated that the junction was electrically abrupt. The dark J(V) characteristics were divided into three regimes, (i) A reverse bias regime in which the device acts as a p-n heterojunction, (ii) an intermediate forward voltage regime, where the derived values of m > 2 indicating the presence of a high density of interface states (iii) High forward regime. All devices deviate from the standard diode equation as a consequence of space charge effects in the organic layer, the ideality factors m"2. Temperature dependence measurements of PbPc/TiO2 heterojunctions show that the junction currents are a composite of tunnelling and recombination. PV cell parameters were influenced by changes in ambient conditions, the thickness of organic layers and variations in incident intensity. The J[sc] and V[oc] were proportionally and logarithmically dependent on the incident intensity respectively. The high R[s] is believed to be responsible for the poor cell efficiencies reducing FF, J[sc] and eta. A 30 fold increase in eta was observed when the organic film thickness was reduced from 500nm to 100nm. Exposure to atmosphere reduced eta and is likely to be a consequence of O2 trapping centres. The work has demonstrated the feasibility of a low cost solid state 10 heterojunction photovolatic cell. However improvements in efficiency are required to produce a commercially viable device.

abstract: A series of pyrite thin films were synthesized using a novel sequential evaporation technique to study the effects of substrate temperature on deposition rate and micro-structure of the deposited material. Pyrite was deposited in a monolayer-by-monolayer fashion using sequential evaporation of Fe under high vacuum, followed by sulfidation at high S pressures (typically > 1 mTorr to 1 Torr). Thin films were synthesized using two different growth processes; a one-step process in which a constant growth temperature is maintained throughout growth, and a three-step process in which an initial low temperature seed layer is deposited, followed by a high temperature layer, and then finished with a low temperature capping layer. Analysis methods to analyze the properties of the films included Glancing Angle X-Ray Diffraction (GAXRD), Rutherford Back-scattering Spectroscopy (RBS), Transmission Electron Microscopy (TEM), Secondary Ion Mass Spectroscopy (SIMS), 2-point IV measurements, and Hall effect measurements. Our results show that crystallinity of the pyrite thin film improves and grain size increases with increasing substrate temperature. The sticking coefficient of Fe was found to increase with increasing growth temperature, indicating that the Fe incorporation into the growing film is a thermally activated process. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2014

5 p. / A description of different methods used in mounting solar photovoltaic (PV) modules or arrays for the residential, commercial, or agricultural user.

5 p. / Solar energy systems can help Arizona individuals, families, and businesses achieve energy conservation goals beyond the adoption of energy-efficient appliances, and LED bulbs. Which type of system is the best? Knowing which system to select is the first important question. This factsheet will focus on solar photovoltaic energy systems. The term photovoltaic refers to the conversion of light energy to electricity.

4 p. / The adoption of solar photovoltaic (PV) energy systems to serve as an energy source for residential, commercial and agriculture applications is growing. Early use of solar PV energy as an alternative energy source to fossil fuels became popular in the 1970’s during the rise of the environmental movement. The cost of solar power in 1977 was $76.00 per watt. A combination of factors including public awareness, demand for solar, availability of product and service, and improving technology has dropped the cost per solar watt. In 2015, the cost of solar power was $0.613 per watt (Shahan, 2014). Energy rebates offered by local, state, and federal agencies has made the adoption of solar energy more affordable.