EFFICIENT LIGHT-TRAPPING IN THIN-FILM SOLAR PHOTOVOLTAICS USING SYMMETRY BREAKINGSang Eon Han, Brittany Hoard, and Reid Collins

Problem: Currently, solar power is too expensive to competewith traditional energy sources. Amorphous silicon solar cellsshow promise in lowering costs; however, they are currentlynot efficient enough to compete.

Goal: To raise the efficiency of thin-film amorphous silicon solar cells through the use of symmetry breaking to allow themto replace thick crystalline cells, thus lowering the cost of implementing solar power.

Approach: We ran absorptance code through computer clusters at the Center for Advanced ResearchComputing to obtain theoretical efficiencies for solar cells with varying degrees of symmetry. These efficiencies are a bit inflated but they still allow fordifferences between different cell types to be seen. It is predicted that the less symmetry that a cell has, the more efficient it will be. Three types, C4v, C4, and C2 were tested with C4v essentially being a control groupbecause it is very symmetrical and C2 having virtuallyno symmetry present.

Results: • C4v had an ultimate efficiency of 32.2%•C4 had an ultimate efficiency of 32.8%•C2 had an ultimate efficiency of 34.6%, although this needsto be modified later because this value does not take silverabsorption into account.

0.3 0.4 0.5 0.6 0.70

0.2

0.4

0.6

0.8

1

Wavelength (μm)

Ab-

sorp

-ta

nce

0.3 0.5 0.70

0.2

0.4

0.6

0.8

1

Wavelength (μm)

Ab-

sorp

-ta

nce

0.3 0.4 0.5 0.6 0.70

0.20.40.60.8

1

Wavelength (μm)

Abso

rpta

nce

C4v C4 C2

Future Direction: The error corrections for C2 stillneed to be made so that the ultimate efficiency for that geometry is accurate. Additionally, further testing needsto be done to determine why C2’s efficiency is strangelylow. To take this project yet another step further, the cellgeometries could be produced experimentally and testedin real-world conditions to determine what the actual efficiencies of the cells are so that they can eventuallybe compared to the top-grade amorphous silicon cellscurrently in use today to determine whether or not symmetry –breaking has had a significant impact.

Nanostructured Gallium Nitride Based Light Emitting Diodes for Solid State Lighting

Jackie ShortridgeArizona State UniversityMentor: Saadat Mishkat Ul MasabihPI: Dr. Daniel Feezell

Screening

Approach

Results Future Work

Problem:

Goal:

Two intrinsic problems that contribute to the low efficiency of present green GaN LEDs are the yellow-green gap, and the efficiency droop.

By using GaN and it’s alloys the entire visible spectrum can be emitted. The goal is to create an industry viable highly efficient green-yellow light emitting diode.

V/III ~ 500

V/III ~ 250

V/III ~ 110

V/III ~ 50

Decreasing V/III RatioIncreases with

increase in

temperature

increases with

decrease in

temperature

• The V/III ratio was decreased to optimize m-plane growth and minimize semipolar plane

• Temperature was varied to increase vertical growth to eliminate coalescing

ITO evaporation followed

by photolitho

graphy

MOCVD growth

of pyramid

al nanostri

pes

Wet etch using 1H2O2:

10 HCl

ICP dry etch to expose underlyi

ng n-GaN

Lithography

followed by n-side

metal evaporat

ion

Electrical Injection

• Continue optimization of microprocessing and nanostripe growth to eliminate current leakage

• Advance to electrical injection and further application use

• By using metal-organic chemical vapor deposition we can achieve selective area growth

• Manipulating the flow rate, balance, time, temperature ect., optimal optical properties can be achieved

• Extensive use of scanning electron microscopes to observe GaN growth and topography.

Self-Assembled Conjugated Polymer Nanostructures:Understanding charge generation and recombination processes in organic photovoltaics

Jordan Ulibarri-Sanchez

University of New MexicoMentor: Alan Thomas

PI: Dr. John Grey

Problem:

Goal:

Results:

Approach:

Future Directions:

Organic solar cells do not have a very high efficiency, the record being 8.4%. There are negativeprocesses that are occurring within the organic polymersthat are yet to be completely determined.

This study is to help determine what processes occur within the organic polymer P3HT (common OP) in orderto be able to mitigate any unwanted effects.

disordered

ordered

P3HT nanofibers can be created in anordered or disordered manner (usingeither toluene or anisole as the solvent).

We can see a major differencejust by fluorescing the two.

H = disordered, J = Ordered

•Efficient quenching in ordered NF’s.•Absence of quenching in air supports triplet generation. •Results support polaron recombination.

1. Bias Dependent experiments1. Places the NF’s in an E field2. Determines the effect of polarizing

the excited state electrons

2. Time Correlated Single Photon Counting experiments

1. A better understanding of short-time dynamics of charges (polarons/excitons) in the NF’s

Optimized Preparation and in vivo Characterization of Monosized Silica Supported Lipid Bilayer Nanoparticles

Kevin HumphreyVanderbilt UniversityMentor: Paul Durfee

PI: Dr. C. Jeffery Brinker

Aim: Monosized Silica Supported Lipid Bilayer Nanoparticles (also called Protocells) were designed to be used as a drug delivery platform for the transport of therapeutic cargo to specific cells inside of a living organism, specifically for the treatment of cancer.

Importance:While current cancer treatments are becoming more effective, there are still major side-effects to these treatments that can be painful and potentially life threatening. The Protocell seeks to offer a potent treatment for cancer that will greatly reduce the normal side-effects associated with cancer therapies.

Approach:A Protocell is formed by loading a mesoporous silica nanoparticle with drugs and fusing a lipid bilayer to the exterior of the particle. We aim to create a drug delivery platform the can deliver multi-component cargo to specific cells in the body with reduced side-effects. This summer’s work focused on optimizing loading conditions as well as stability of the

Results:

Protocell by changing the lipid composition, temperature and drug concentration, and then characterizing them with in vitro and in vivo studies.

Type of Lipid RT (% loaded) 4C (% loaded)DOPC 6.18 13.91DOPC/PEG 6.51 14.44DSPC 6.15 13.27DSPC/PEG 3.56 9.19Bare 4.48 10.60Average 5.38 12.06

Monosized MSNP

Monosized Protocell

Future Direction:• Reducing Particle Size• In vitro Drug Release• Loading Different Cargo• Cell Targeting• Comparing the Protocell to Doxil (liposomal delivery)

PROBLEM:Current efficiencies for polymeric based solar cell devices are much lower than silicon based ones. They cannot compete with higher efficiency solar cells in cost production or energy production.

GOAL:The study focuses on fabricating advanced light trapping structures to incorporate in solar devices. The structures hoped to be created are positive nano-pyramids and inverted nano-pyramids. These structures will be made on silver, and can be used in many different photovoltaic devices.

METHOD:Silicon wafers are etched using a combination of dry and chemical etching. The etching produces an inverted pyramidal structure on the surface of the silicon. Next the entire surface of the silicon is coated with silver using electron beam deposition. After the surface is coated, an adhesive layer is attached to silver and the silver is removed with the adhesive.. All steps are analyzed under scanning electron microscope.

RESULTS: FUTURE STUDIES:

Enhanced Light Trapping for Polymeric Photovoltaics

Michael FlammiaMentor: Swapnadip GhoshPI: Sang M. Han

Positive Silver Pyramids

Inverted Silver Pyramids

• Investigate different adhesives and their abilities to effectively remove silver layers.

• Use of sacrificially layers deposited on top of silicon before silver. This has potential to make removal of the silver layer much easier.

Silver peeling with sacrificial layer.

GoalAssess the permeablization of gram negative E. coli k12 T7 by cationic mesopourous silica nanoparticles to explore the particles potential as a drug delivery and enhancement technique.

BackgroundAntibiotic resistant bacteria kill 23,000 people in the U.S. annually. Specifically gram negative bacteria present a formidable barrier to conventional antibioticsnecessitating new treatments to combat these increasingly deadly infections.

Results• Cationic Silica Nanoparticles permeabilize E. coli K12

T7 in a concentration dependent manner.• Cationic Silica Nanoparticles increase the uptake of

hydrophobic and hydrophilic antibiotics in E. coli K12 T7.

• The permeablization and binding of the cationic silica nanoparticles decreases as the bacteria multiply.

Procedure

We tested four types of cationic silica nanoparticles 25 nm and 50 nm spheres and 100 nm and 200 nm rods. We used NPN fluorescent dye to measure the permeabilization of the E. coli. And measured the optical density of the growing bacteria to assess the synergy between the antibiotics and the particles.

ASSESSMENT OF BACTERIAL MEMBRANE PERMEABILITY USING CATIONIC SILICA NANOPARTICLE PLATFORMS

50 nm Particles on surface of E. coli

By Alexander ProssnitzMentor: Dr. Jacob AgolaPI: Professor Jeffery Brinker

Development of an Earth Abundant Catalyst that Completely Dehydrogenates Methanol

Michael Bender, Daniel T. Yonemoto, Timothy J. Boyle

Why Study This?• Fossil fuel consumption is not sustainable• Hydrogen fuel cells are an

alternate energy source• Methanol has the potential to be

an excellent hydrogen carrier• Development of this catalyst

would allow methanol to replace fossil fuels in cars

Synthesis of Potential Catalysts

Ti(ONep)(A.L.)

Approach• Seek to replace the rare and expensive

Ru in this effective catalyst with an earth-abundant substitute

N

PR2PR2

NHO

OH

OH

• The following pincer and pincer-like alkoxy ligands are bound to earth abundant metals

R=Pri, But

Pincer ligands synthesized by the Kemp Group

Alkoxy ligand synthesized by Farrell Group

P.L.(Pri) P.L.(But) A.L.

Zr2(ONep)2(A.L.)2 Zr2(OBut)5(A.L) Ti2(ONep)5(A.L)

Ti(OBut)(A.L.)

• Work has focused so far on pincer-like alkoxy ligand

• A variety of group 4 metal alkoxides have been synthesized

Future Work

• Synthesize potential catalysts using the pincer ligands

• Explore more first row transition metals, such as Fe and Co

• Send synthesized compounds to Sandia-CA’s facilities for catalytic testing

PEM fuel cell

Problem

Objectives

Future Work

1. Evaluate the changes made on the secondary and tertiary structure of the protein induced by the CPEs/OPEs.

2. Study the effects of UV/Visible light irradiation on the structural stability of protein and CPEs/OPEs.

3. Evaluate the effect of protein interaction on the conformation of the CPEs/OPEs

1. Continue thermal stability studies using CD (25°C – 95°C)

2. Continue with Fluorescence studies

3. Determine changes made to the Chemical Structure of Lysozyme and BSA

a) SDS-PAGE (Sodium dodecyl sulfate - Polyacrylamide Gel Electrophoresis)

b) RP-HPLC (Reverse Phase - High Performance Liquid Chromatography) Using tryptic digest

c) SE-HPLC (Size Exclusion - High Performance Liquid Chromatography)

4. Perform studies on spore coat protein

Interaction of Conjugated Polyelectrolyte Polymers and Oligomers with Protein

Lysozyme

Results

Hira AhmedNorth Carolina State University

Mentor: Greg SolizPIs: Dr. Eva Y. Chi & Dr. David

G. Whitten

Emergence of multi-drug resistant pathogens has threatened the effective prevention and treatment of infections worldwide. This lead to the synthesis of new class of Phenylene ethynylene (PPE)-based conjugated polyelectrolyte polymers (CPEs) and oligomers (OPEs) antimicrobial agents that do not induce resistance. These CPEs and OPEs exhibit significant light-enhanced biocidal activity caused by the reactive oxygen species against a range of pathogens, such as bacteria, viruses, and spores.GoalTo gain a better understanding of how the selected CPEs and OPEs induce toxicity to the model viruses on a molecular level, using the model protein Lysozyme. Since these antimicrobial activities of these compounds are believed to arise from their interaction with the envelope and capsid of their targets which are mainly composed of proteins.

1. Circular-Dichroism (Far-UV CD) Spectroscopy: To determine the changes made to the secondary structure of the protein produced by CPEs/OPEs.

2. Fluorescence Spectroscopy: To determine the changes made to the tertiary structure of the protein produced by CPEs/OPEs and to evaluate the effect of proteins on CPE/OPE conformation.

HPLC

PPE-DABCO have shown to effect the secondary and tertiary structure of Lysozyme. PPE-Th and EO-OPE (C2) also showed similar results.

PPE-DABCO

PPE-Th

EO-OPE (C2)

Research Methods

Selected CPEs/OPEs

SDS-PAGE

MotivationThe high efficiency of III-V multijunction photovoltaics make III-V semiconductors the optimal material to use in solar cells. However, concerns about the high cost of these materials have prevented their widespread implementation and use. Creating thin film dual GaAs/GaSb diodes may be the solution to this problem.

ObjectivesThough various substrate removal and epitaxial lift-off methods have been shown to work for GaAs, the isolation of thin film GaSb has yet to be successfully completed. This project focuses on epitaxial lift-off (ELO) of semiconductor thin film structures grown through molecular beam epitaxy.

Future Work•Further optimize the ELO process for GaSb films•Further investigate the surface composition of GaSb•Fabricate thin film devices for use as solar cells

Structure A

Structure B

Results

Procedure

•Epitaxial lift off was possible for all three structures, and each method produced results with varying success.•Adding a copper layer reduces cracking on the thin films•The surface quality of the GaSb films can be improved by using a protective GaAs layer.

Control Structure

Characterizing Compound Semiconductors for Solar Cell Development

J.C. Roberts, E.J. Renteria, and G. Balakrishnan

•Three structures were chosen for investigation

•Etchant solution selectivity was explored

•Black wax method was used to induce ELO

•Results were characterized

•Methods were refined for maximum optimization

OOZachary SchafferMentor: Wenhan He

PI: Dr. Yang Qin

UNM NSMSREU 2014

Quantum Dot Integration in Ordered Bulk Heterojunction Organic Photovoltaics

Goals

Establish method for safe, size tunable production of cadmium selenide quantum dots.

Increase organic photovoltaic light absorption range through addition of CdSe quantum dots.

Increase power generation of organic photovoltaics by matching absorption range to solar spectrum.

Approach

Attach CdSe quantum dots to self assembled P3HT nanofiber via pi-pi interactions.

Tune quantum dot size in order to change HOMO and LUMO energy values and allow cascade of electrons from donor polymer through quantum dot to acceptor polymers.

Future Directions

Analysis of reaction pathway via ultrafast transient absorption spectroscopy conducted at CINT Sandia.

Results

Successful creation of properly sized, monodisperse, defect free CdSe quantum dots.

Successful attachment of the quantum dots to self assembled P3HT nanofiber.