Spotlight shines on solar power, lighting research


March 13, 2009

Imagine flexible lighting devices manufactured by using printing techniques. Imagine solar power sources equally as reliable and as portable as any conventional power source.

Such advances are among aims of research at Arizona State University to find ways of more effectively harnessing solar power and producing more energy-efficient, durable and custom-designed light sources. The work is now drawing support from two international corporations. Download Full Image

U.S.-based Solterra Renewable Technologies Inc. and Nitto Denko Technical-NDT of Japan are investing more than $3.7 million through grants to help fund the research led by ASU engineering professor Ghassan Jabbour.

Jabbour’s work focuses on the use of nanomaterials and quantum dots in solar cells and solid state lighting. Technical advances in this area “will open the way for a new wave of more efficient and portable power and light sources in as many shapes and varieties as designers can imagine,” he says.

Jabbour, who teaches in ASU’s School of Materials, is doing his research through the Advanced Photovoltaics Center, which he directs. The center is part of the Arizona Institute for Renewable Energy at ASU. Jabbour also is director of optoelectronics research for the Flexible Display Center, part of the univerisity’s Ira A. Fulton School of Engineering.

Illuminating printing processes

Work funded by the grants will include the study of the materials science, physics and engineering solutions necessary to produce the next generation of solar cells, which will cost less to produce and perform more efficiently, Jabbour says.

The project is an example of the economic benefit a research university can bring to its state. Each year, Arizona universities contribute nearly $1 billion into the Arizona economy from their research, most of which is funded by the U.S. government and entities from outside the state. Research money brought in by universities is restricted money that can be used only for the research activity it supports. It cannot be used to compensate for cuts in other parts of the university’s budget.

The quantum dots/solar cells project already has brought a small company to open new operations at the ASU Research Park. Given the increasing interest in solar energy and the means to produce it at lower costs, the company can be expected to grow rapidly, Jabbour says.

One of the major scientific and engineering challenges of Ghassan’s project involves how to employ printing techniques to fabricate low-cost alternatives to current solar cells. Research articles on printed organic solar cells written by Jabbour and other members of his team continue to be cited by fellow researchers more than any other articles in the area of printed ultra-thin solar area research. (Ultra-thin means it involves materials less than 100 times the thickness of a typical human hair.)

Printing is a viable method for mass production of solar cells. Some printing techniques, such as silk-screen printing (commonly used to print logos, numbers and pictures on textiles), are already used in some aspects of solar cell manufacturing.

Printing allows for large numbers of solar-cell devices to be manufactured rapidly, thus eventually bringing down costs.

“In our work, we will be investigating various techniques such as inkjet printing, screen printing, and roll-to-roll, which is similar to newspaper printing techniques, to see what works best for solar cell manufacturing,” Jabbour says.

The power of photons

The material science and engineering aspect of the projects involves experiments with materials that exhibit unique properties at the nanoscale, specifically materials that use photons to achieve more efficient conversion of energy into electricity. The materials also have a broader absorption spectrum of incident solar light – meaning they can make more effective use of solar light for conversion into electricity.

“It’s traditional to generate one electron-hole pair for every absorbed photon in most solar cells,” Jabbour says, but researchers in his lab are working on generating more multiple electron-hole pairs per photon to achieve increased power-conversion efficiency. This is accomplished by producing a higher number of electrons for each absorbed photon from incident light.

In most bulk semiconducting materials, Jabbour explains, absorption of an incident photon (light quanta) with the right energy can excite an electron enough to move it across an energy band gap – thus resulting in an electron-hole pair. But the same photon might generate more than one electron-hole pair if the material is made into much smaller dimensions – such as the size of a quantum dot.

Quantum dots are small particles about few nanometers (a billionth of a meter) in size. By adjusting the particles’ physical dimensions, their optical and electronic properties can be fine-tuned. Through such a process, the resulting characteristics of the materials are different than the characteristics of the same material in bulk size, Jabbour explains.

The challenge is how to extract most of the charges from the dots to transfer in the form of electrical current to the device being powered by the solar cell, he says.

Recent results of 3 percent in power conversion in this area are encouraging. Such an efficiency will continue to climb as better materials and device structures are being developed, which is a part of Jabbour’s work supported by the grants.

Energy conservation goals

More efficient solar cells are only one part of the solution to the nation’s growing energy needs. Just as important is making efficient use of energy in conventional systems, Jabbour says.

The two technologies he and his team are working on are interrelated, involving both energy generation and energy conservation. Although there is a strong push for alternative energy, including solar energy, Jabbour says much can be accomplished by focusing on research to lower the power consumption of conventional technologies. This work involves the area of solid state lighting.

One of the corporate grants is supporting work directly aimed at understanding the materials and device physics of nanoscale structures for low-power, nanothick solid state lighting applications.

The materials used are hybrid nanomaterials targeting white-light emission from a single building block. The light source made out of these materials also will have a nano-range thickness and can be operated at high brightness (equivalent to a ceiling lamp) using a 9-volt battery source. Just as with solar cells, these light sources will also be printable in the future, Jabbour says.

Flexibility in lighting devices

“The beauty of these two projects is their compatibility with rugged substrates, including flexible ones,” he says.

A substrate is a material on which circuits or other small devices are formed or fabricated. Flexible substrates (for example, plastic, thin metal foils, or cloth) allow for more durable lights that also weigh less than conventional lighting devices and can be produced in a variety of shapes.

“Imagine a light that is made on a roll that can be cut into various shapes according to the desire of the user,” Jabbour says. Such an advance is still far off, but not impossible. In fact, he points out, printed lights made out of inorganic phosphors that operate at about 120 to 150 volts are already available. The drawback is that currently they can be operated only at such high voltages.

The two technologies promise to provide low-cost, high-efficiency solar cells and solid state lights that can be made on thin flexible substrates, resulting in light-weight durable modules that are easier to place on roof tops (for example, solar-cell arrays) and indoors (lamps and similar lighting devices).

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering

480-965-8122

Greater Phoenix resale numbers show transactions jump for February


March 13, 2009

February 2009 resale activity experienced an upsurge of 8,510 resale homes recorded sold, while there were 6,960 recorded sales in January and 4,675 sales for a year ago. However, foreclosure activity in February 2009 represented 51 percent (4,295 transactions), while there were 4,215 traditional market transactions.

Foreclosure transactions represent home owners losing their property to successful individual bidders or the lender of record.  For February 2008, there were 1,985 sales in foreclosure or 42 percent on the month’s recordings.    Download Full Image

For February 2009, foreclosure activity differed throughout the Valley such as 48 percent in Surprise, 51 percent in Glendale and 40 percent in Scottsdale. Even in response to hiatus and mortgage modification programs, foreclosure activity did not slow.

“Due to the time it takes to record transactions, some slowing might still be evident in the next few months,” said Jay Q. Butler, director of Realty Studies in Arizona State University’s Morrison School of Management and Agribusiness at the Polytechnic campus. “However, the fundamental problem remains that an extremely weak economy is leading to mounting job losses that could severely impact the ability of a troubled household to have the needed income to qualify for one of the possible programs or even have the needed income to maintain ownership.”

The declining prices have piqued interest for potential investors and owner-occupants, especially in the lower income ranges. For the traditional market, the median price in February was $133,000 ($230,000 for February 2008), while the foreclosed properties had a median price of $164,470 ($193,440 for February 2008).

The fundamental reason why the median price for foreclosed homes is higher than traditional transactions is more expensive homes were foreclosed on in February, such as nearly 20 homes over $1 million (only 8 homes in January), and 7 percent of the foreclosures were in the $300,000 range (4 percent in January). Another reason is that for the last year, slightly more than 30 percent of the traditional sales were foreclosed homes that were sold again with a median price markdown of 15 percent. The markdown varied throughout the Valley ranging from 44 percent in Maryvale to 17 percent in Avondale to 9 percent in Tempe.

Since the Greater Phoenix area is so large, the median price can range significantly. For February 2009 in North Scottsdale, the median price for a foreclosed property was $405,035 ($443,470 in January), while the traditional market was $511,765 ($489,000 in January). In South Scottsdale the splits were $200,000 ($195,350 in January) and $195,000 ($221,450 in January), respectively.

In Maryvale, traditional transactions were $39,900 ($41,000 in January) and foreclosures were $118,655 ($81,730 in December), while in Union Hills it was $205,000 ($220,000 in January) and $199,850 ($186,780 in January), respectively. For February 2009, Paradise Valley had a median square footage of 4,100 and a median price of $1,050,000. 

While lower prices can greatly improve affordability, they can adversely impact many owners and potential sellers whom are watching their limited equity erode, as prices decline to and even below existing debt level. Rapidly declining value can be another issue in some of the mortgage modification programs which require a limited decline in value from the purchase and financing of the home.

Within the 940 total recorded sales for February 2009, the townhouse/condominium market had 490 foreclosed properties.  For a year ago, there were 700 total transactions with 150 being foreclosures. In February 2009, the median price for foreclosed properties was $128,395, while the traditional market stood at $121,000. Last year, the respective splits were $149,800 and $170,000.

The median square footage for a single-family home recorded sold as foreclosed in February was 1,680, and 1,715 square feet for a market transaction home. For a year ago, the foreclosed market was at 1,725 square feet, and the traditional market stood at 1,770 square feet.  In the townhouse/condominium sector, the median square footage for a foreclosed unit was 1,070 square feet (1,090 square feet for year ago), while the traditional market unit was 1,165 square feet (1,090 square feet for a year ago).

February 2008-- SINGLE-FAMILY RESALE HOMES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix 1,190 $176,900 590 $200,000 600 $165,090
Scottsdale 275 513,300 225 522,500 50 485,000
Chandler 260 245,000 190 251,000 70 222,210
Gilbert 325 254,400 190 250,000 135 258,295
Mesa 475 204,500 310 212,075 165 190,545
Tempe 90 240,000 65 247,000 25 213,120
Avondale 160 197,405 70 187,500 90 209,320
El Mirage 90 151,905 35 147,000 55 157,125
Glendale 315 198,050 160 212,000 155 184,500
Goodyear 160 216,925 75 256,500 85 203,895
Peoria 225 224,690 125 235,000 100 199,000
Sun City 95 170,000 85 167,500 10 226,340
Sun City West 55 209,000 55 205,000    
Surprise 285 212,640 150 222,000 135 200,000
             
County 4,675 $214,500 2,690 $230,000 1,985 $193,440
January 2009 -- SINGLE-FAMILY RESALE HOMES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix 2,425 $90,675 1,190 $74,500 1,235 $104,460
Scottsdale 255 380,000 165 387,000 90 376,000
Chandler 305 204,000 165 230,000 140 192,590
Gilbert 360 197,250 195 200,000 165 189,900
Mesa 645 138,000 335 140,000 310 134,900
Tempe 80 205,000 50 219,500 30 175,800
Avondale 255 115,000 120 114,900 135 115,570
El Mirage 155 85,000 85 76,125 70 94,000
Glendale 505 130,000 250 125,000 255 134,000
Goodyear 195 150,000 115 145,000 80 156,375
Peoria 310 171,310 145 171,950 165 171,310
Sun City 60 140,340 40 132,500 20 150,225
Sun City West 40 219,000 40 219,000    
Surprise 410 144,000 200 142,900 210 144,000
             
County 6,960 $135,335 3,590 $136,000 3,370 $135,005
February 2009 -- SINGLE-FAMILY RESALE HOMES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix
2,835 $104,900 1,370 $65,000 1,465 $138,210
Scottsdale
325 395,000 195 434,000 130 369,225
Chandler
355 197,500 180 200,000 175 194,910
Gilbert
455 208,000 230 200,000 225 220,930
Mesa
780 144,500 385 135,000 395 157,260
Tempe
75 190,000 50 209,500 25 181,780
Avondale
340 120,540 155 112,000 185 143,485
El Mirage
195 90,000 90 71,900 105 117,500
Glendale
585 134,220 285 121,000 300 145,630
Goodyear
250 170,490 110 155,000 140 178,885
Peoria
380 179,905 190 169,900 190 190,000
Sun City
100 136,000 70 129,450 30 208,425
Sun City West
35 190,000 30 190,000 5 240,635
Surprise
495 154,260 255 140,000 240 175,000
             
County 8,510 $150,000 4,215 $133,000 4,295 $164,470
February 2008 -- TOWNHOUSE-CONDOMINUM RESALES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix 215 $145,200 150 $153,850 65 $133,595
Scottsdale 175 250,000 140 264,705 35 224,000
Chandler 25 160,900 20 162,000 5 142,775
Gilbert 5 180,000 5 180,000    
Mesa 80 134,810 60 144,000 20 103,970
Tempe 40 160,000 35 159,500 5 179,850
Avondale            
El Mirage            
Glendale 15 118,530 10 131,000 5 110,270
Goodyear            
Peoria 15 178,500 15 178,500    
Sun City 50 122,750 50 123,000    
Sun City West 15 130,000 15 130,000    
Surprise            
             
County 700 $164,950 550 $170,000 150 $149,800
January 2009 -- TOWNHOUSE-CONDOMINUM RESALES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix 235 $106,000 105 $116,000 130 $97,650
Scottsdale 105 195,000 75 210,000 30 169,375
Chandler 30 88,850 15 79,900 15 116,785
Gilbert 10 127,850 5 192,000 5 99,835
Mesa 75 83,600 35 79,000 40 87,320
Tempe 20 157,000 15 129,250 5 187,610
Avondale            
El Mirage            
Glendale 30 72,000 10 60,000 20 91,000
Goodyear            
Peoria 15 144,585 10 129,750 5 148,750
Sun City 30 98,500 25 98,500 5 94,705
Sun City West 10 142,000 10 142,000    
Surprise            
             
County 615 $115,000 335 $125,000 280 $104,745
February 2009 -- TOWNHOUSE-CONDOMINUM RESALES
Selected Cities Total Median Price Traditional Sales Median Price Foreclosed Sales Median Price
Phoenix
390 $115,000 140 $114,000 250 $119,500
Scottsdale
170 175,000 105 169,900 65 186,915
Chandler
25 133,000 10 133,000 15 138,640
Gilbert
20 140,915 10 139,500 10 168,725
Mesa
85 106,900 45 110,000 40 106,800
Tempe
35 131,765 20 117,000 15 134,100
Avondale
           
El Mirage
           
Glendale
55 85,000 20 58,860 35 92,900
Goodyear
           
Peoria
15 82,600 10 126,500 5 82,290
Sun City
50 105,000 40 100,375 10 124,820
Sun City West
10 132,450 10 132,450    
Surprise
10 109,625 5 96,000 5 142,315
             
County 940 $125,000 455 $121,000 485 $128,395

Realty Studies is associated with the Morrison School of Management and Agribusiness at Arizona State University’s Polytechnic campus. Realty Studies collects and analyzes data concerning real estate in the greater Phoenix metropolitan area. Realty Studies is a comprehensive and objective source of real estate information for private, public and governmental agencies. Its director, Dr. Jay Q. Butler, may be reached at (480) 727-1300 or e-mail him at Jay.Butler">mailto:Jay.Butler@asu.edu">Jay.Butler@asu.edu. To subscribe to RSS feed for Realty Studies news, visit http://www.poly.asu.edu/realty/rss.html">http://www.poly.asu.edu/realty/rss.html">http://www.poly.asu.edu/realty/....

Jay Butler, Jay.Butler">mailto:Jay.Butler@asu.edu">Jay.Butler@asu.edu
(480) 727-1300

Chris Lambrakis, lambrakis">mailto:lambrakis@asu.edu">lambrakis@asu.edu
(480) 727-1173
Public Affairs at ASU Polytechnic campus