Helio Volt Corporation The Future of Photovoltaic Power

Helio. Volt Corporation: The Future of Photovoltaic Power B. J. Stanbery Helio. Volt Corporation 8201 E. Riverside Dr. , Suite 600 Austin, TX 78744 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation UT Ch. E Prof. T. F. Edgar

Helio. Volt Mission l To develop and commercialize a new generation of efficient, safe, reliable, and attractive thin-film photovoltaic solar power products that are the first to enable energy production at cost parity with conventional sources of electricity. 20 Nov 2007 Cost • Lowest cost thin film circuits, less than one fourth that of silicon PV and one tenth that of current Building Integrated PV (“BIPV”) products Durability • Warranted Lifetime of at least 20 years for first products Efficiency • Comparable conversion efficiencies to multicrystalline silicon Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 2

Solar Power Learning Curve l Plateau in direct manufacturing costs l Data source Luuk Beurskens, ECN Policy Studies, PHOTEX’ 03 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 3

Lifetime Required for 10¢/k. W·h Energy at Various Module Costs 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 4

Solar Power Yesterday l Silicon Photovoltaic (PV) modules for retrofit l PV module sales $5. 5 B (2005) – PV market 30+% CAGR since ‘ 97, +40% 2005 Sales <½% total annual global Cap. Ex for electrical power generation l Current market limited by supply, even at price of l – $4/Wp modules + $3 installation = $7/Wp 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 5

Silicon Module Limitations $1. 78/Wp projected lowest cost for crystalline Si PV modules l Over $1 in silicon materials cost dominates COGS • Data source Prog. Photovolt. Res. Appl. 5, 309 -315(1997) 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 6

Semiconductor Cost Reduction 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 7

Solar Power Tomorrow l Power Buildings will become multi-$T market – PV as an integrated electronic component Efficient, durable thin-film solar cells incorporated into traditional building materials l Current products unsuitable for this market Energy Technology & Policy 20 Nov 2007 l B. J. Stanbery, Helio. Volt Corporation 8

Power Buildings Market Huge latent demand l USA potential: $150 B/yr l – 60% share l Multiple segments – Architectural glass – Windows & skylights – Roofing 20 Nov 2007 Electrical Demand met by PV Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 9

Reactive Transfer Printing Plate Precursor 2 Stage 1: Precursors’ Deposition Substrate Precursor 1 Stage 2: Rapid Thermal Processing and Separation Heat Mechanical (& Electrostatic) Pressure Product Layer Micro-Reactor 20 Nov 2007 Printing Plate Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation Substrate 10

CIGS PV Device Semiconductor: Copper Indium Gallium Diselenide l Highest efficiency single-junction thin-film PV semiconductor material – 19. 5% conversion efficiency (NREL) – Unique material properties derive from spontaneous nanostructuring l Inherently stable under normal operating conditions l Second generation photovoltaic semiconductor material 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 11

RTP Implementation: FASST ™ CIGS Semiconductor Synthesis l Field-Assisted Simultaneous Synthesis and Transfer • Second generation CIGS manufacturing technology l Advantages – Rapid processing – Vastly reduced thermal budget – Confinement of volatile selenium – Electrostatic field effects on ionic constituent transport during synthesis 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 12

FASST ™ Process Sequence Rapid Thermal Processor Electrostatic Chuck Printing Plate Release Layer Precursor 2 Precursor 1 Metal Contact Layer Substrate Flash Heating Recoat Printing Plate Release Layer Device Processing emitter CIGS Metal Contact Layer Substrate Completed Device 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 13

First Factory Production Flow 1. Front End Glass Clean Metal Deposition 2. CIGS Synthesis Precursor Deposition FASST ™ Synthesis 4. Device Processing Absorber Pattern (P 2) TCO Deposition 5. Back End Product Packaging 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation Metal Pattern (P 1) Buffer Deposition 3. Buffer TCO Pattern (P 3) Test & Ship 14

CIGS Thin-Film Products • • • 20 Nov 2007 CIGS is an alloy of Copper, Indium, Gallium and Selenium Monolithic integration forms circuits without high wafer assembly costs CIGS is one of three known intrinsically stable PV materials (with Silicon and Gallium Arsenide) • Instrinsic stability required for long lived robust products More efficient absorber of light than any other known semiconductor Requires 1/100 th of the material compared to silicon for comparable light absorption Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 15

Product Value Proposition Revolutionary FASSTTM Manufacturing Process CIGS Thin. Film Technology Helio. Volt Thin-Film PVICs • Highest performance; most versatile & durable • PVIC platform avoids costly inter-cell wiring & bypass components • Proven semiconductor CIGS (Copper Indium Gallium Selenide) • Lowest Cost Thin Film Devices • Less than 1/4 th the cost of silicon PV module • Integrated systems for Power Buildings less than 1/10 th cost of current technologies • Lower cost electricity than effective current retail electricity prices in five years • Wide Range of Applications for both rigid and flexible PVIC platform products • Traditional PV modules • Building Integrated PV (BIPV) Systems 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 16

Reactive Transfer Printing (RTP) l Combines features of – Rapid Thermal Annealing, and (optionally) – Anodic Wafer Bonding • electrostatic fields effects l Advantages – Rapid processing • Eliminates pre-reaction • Independent pre-heating of precursors – Confinement of volatile species – Independent precursor deposition optimization 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 17

Rapid Thermal Annealing (RTA) l RTA is a non-equilibrium thermal processing method widely used in semiconductor device manufacturing – Often used to provide activation energy whilst minimizing concomitant diffusion – Employed formation and annealing of gate dielectric layers in FET’s – Used for reactive formation of electrical contacts by thermal silicidation of silicon/metal interfaces 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 18

CIGS Film Process Time l Rapid processing delivers high capital efficiency Metal Selenization Coevaporation Helio. Volt FASST ™ 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 19

Thermal Budget Comparison 20 Nov 2007 l One to three orders of magnitude reduction in thermal budget Figure of Merit (FOM) l Highest average processing temperature Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 20

Anodic Wafer Bonding (AWB) AWB is widely used for MEMS manufacture l Employs electrostatic fields to bond alkali glass to semiconductors or metals with lower temperature and pressure than fusion bonding l High voltage across the wafer/glass stack repels mobile ions in the glass, inducing a space-charge and creating strong electrostatic compression, pulling them into intimate contact on an atomic scale. l 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 21

Electrostatic Compression l Helio. Volt’s FASST™ CIGS process utilizes both mechanical and electrostatic compression – Length scale is much smaller than conventional AWB 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 22

CIGS Precursor Deposition Methods l Low-temperature vacuum deposition – Provides increased throughput compared to conventional high-temperature CIGS synthesis by co-deposition or selenization l Non-vacuum liquid precursor deposition – Helio. Volt/NREL Cooperative Research & Development Agreement (CRADA) • Goal: development of non-vacuum nanomaterialbased precursor deposition processes – Synthesis of CIGS demonstrated using FASST™ processing • Details to be presented by Jennifer Nekuda at the Fall 2007 MRS meeting in Boston later this month 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 23

Recrystallization of Nanoscale Granular Precursor Films l FASST™ CIGS cross-section 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation Precursor Film 24

Composition Fluctuations and Carrier Transport in CIGS PV Absorbers l Peculiar semiconductor behavior: Copper Indium Gallium Selenide (CIGS) PV devices insensitive to extended defects and ± 5% atomic composition variations of its metallic constituents – Selenium deficiency results in poor devices l Observations – CIGS PV devices are always copper deficient compared to a-Cu. In. Se 2 – Compositions lie in the equilibrium a+b 2 -phase domain 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 25

Composition Fluctuations and Carrier Transport in CIGS PV Absorbers l Experimental results* HAADF-TEM & nano-EDS – 5 -10 nm characteristic domain size (2 -D) – Pearson productmoment statistical correlation between the two variables Cu/(In+Ga) and Ga/(In+Ga) is 0. 72 (null P=0. 3% ) 20 Nov 2007 *Applied Physics Letters, 87, 2005, 121904 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 26

Reactive Transfer Printing for Film Synthesis l RTP is an advanced printing method for making films and coatings. It offers – Low thermal budget – Confinement of volatile reaction components – Electrostatic modification of ionic transport l FASST™ implementation of RTP is a processing method with demonstrated capabilities to – Utilize nano-particle based precursors for high-quality CIGS synthesis – Modify nanodomain formation during CIGS synthesis 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation 27

Helio. Volt Corporation: The Future of Photovoltaic Power B. J. Stanbery Helio. Volt Corporation 8201 E. Riverside Dr. , Suite 600 Austin, TX 78744 20 Nov 2007 Energy Technology & Policy B. J. Stanbery, Helio. Volt Corporation UT Ch. E Prof. T. F. Edgar