Indium tin oxide (ITO), the transparent conductor metal films for smart phone, tablet and TV displays

476
A figure showing the crystal structure of strontium vanadate(orange) and calcium vanadate (blue). The red dots are oxygen atoms arranged in 8 octohedra surrounding a single strontium or calcium atom. Vanadium atoms can be seen inside each octahedron.
A figure showing the crystal structure of strontium vanadate(orange) and calcium vanadate (blue). The red dots are oxygen atoms arranged in 8 octohedra surrounding a single strontium or calcium atom. Vanadium atoms can be seen inside each octahedron.

A new material that is both highly transparent and electrically conductive could make large screen displays, smart windows and even touch screens and solar cells more affordable and efficient, according to materials scientists and engineers at Penn State who have discovered just such a material.

Indium tin oxide (ITO), the transparent conductor that is now used for more than 90 percent of the display market, has been the dominant material for the past 60 years. But in the last decade, the price of indium has increased dramatically. Displays and touchscreen modules have become a main cost driver in mobile devices, such as smartphones and tablets, making up close to 40 percent of the cost. While memory chips and processors get cheaper, following Moore’s Law, smartphone and tablet displays get more expensive from generation to generation. Manufacturers have searched for a possible ITO replacement, but until now, nothing has matched ITO’s combination of optical transparency, electrical conductivity and ease of fabrication.

In a paper appearing today(Dec 15) online in Nature Materials, Roman Engel-Herbert, assistant professor of materials science and engineering, and his team report a new design strategy that approaches the problem from a different angle. The researchers use thin (10 nanometer) films of an unusual class of materials — called correlated metals — in which the electrons flow like a liquid. While in most conventional metals, such as copper, gold, aluminum or silver, electrons flow like a gas, in correlated metals, such as strontium vanadate and calcium vanadate, they move like a liquid. In this paper, the authors explain why these correlated metals show a high optical transparency despite their high, metal-like conductivity.

“We are trying to make metals transparent by changing the effective mass of their electrons,” Engel-Herbert says. “We are doing this by choosing materials in which the electrostatic interaction between negatively charged electrons is very large compared to their kinetic energy. As a result of this strong electron correlation effect, electrons ‘feel’ each other and behave like a liquid rather than a gas of non-interacting particles. This electron liquid is still highly conductive, but when you shine light on it, it becomes less reflective, thus much more transparent.”

To better understand how they achieved this fine balance between transparency and conductivity, they turned to a materials theory expert, Professor Karin Rabe of Rutgers University.

“We realized that we needed her help to put a number on how ‘liquid’ this electron liquid in strontium vanadate is,” Engel-Herbert says.

Rabe helped the Penn State team put together all the theoretical and mathematical puzzle pieces they needed to build transparent conductors in the form of a correlated metal. Now that they understand the essential mechanism behind their discovery, the Penn State researchers are confident they will find many other correlated metals that behave like strontium vanadate and calcium vanadate.

Lei Zhang, lead author on the Nature Materials paper and a graduate student in Engel-Herbert’s group, was the first to recognize what they had discovered.

“I came from Silicon Valley where I worked for two years as an engineer before I joined the group. I was aware that there were many companies trying hard to optimize those ITO materials and looking for other possible replacements, but they had been studied for many decades and there just wasn’t much room for improvement,” says Zhang. “When we made the electrical measurements on our correlated metals, I knew we had something that looked really good compared to standard ITO.”

Currently indium costs around $750 per kilogram, whereas strontium vanadate and calcium vanadate are made from elements with orders of magnitude higher abundance in the earth’s crust. Vanadium sells for around $25 a kilogram, less than 5percent of the cost of indium, while strontium is even cheaper than vanadium.

“Our correlated metals work really well compared to ITO. Now, the question is how to implement these new materials into a large scale manufacturing process. From what we understand right now, there is no reason that strontium vanadate could not replace ITO in the same equipment currently used in industry,” says Engel-Herbert.

Along with display technologies, Engel-Herbert and his group are excited about combining their new materials with a very promising type of solar cell that uses a class of materials called organic perovskites. Developed only within the last half dozen years, these materials outperform commercial silicon solar cells but require an inexpensive transparent conductor. Strontium vanadate, also a perovskite, has a compatible structure that makes this an interesting possibility for future inexpensive, high-efficiency solar cells.

Engel-Herbert and Zhang have applied for a patent on their technology. Along with Zhang and Engel-Herbert, coauthors on the paper titled “Correlated metals as transparent conductors” are Hai-Tian Zhang, Craig Eaton, Yuanxia Zheng and Matthew Brahlek, all students and postdoctoral Fellows in Engel-Herbert’s group. Others from Penn State and the Materials Research Institute include Moses Chan, Evan Pugh professor of physics, and his postdoctoral Fellow Weiwei Zhao, and Venkatraman Gopalan, professor of materials science and engineering and his student Lu Guo. Rabe and her student Yuanjun Zhou, Rutgers University, and Anna Barnes, Hamna Haneef and associate professor Nikolas Podraza, University of Toledo also contributed on this project.

The Office of Naval Research, the National Science Foundation and the Department of Energy funded this work. Fabrication of the correlated metals was performed at the Materials Research Institute in the laboratory facilities of Penn State’s Millennium Science Complex.


Story Source:

The above post is reprinted from materials provided by Penn State Materials Research Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. Lei Zhang, Yuanjun Zhou, Lu Guo, Weiwei Zhao, Anna Barnes, Hai-Tian Zhang, Craig Eaton, Yuanxia Zheng, Matthew Brahlek, Hamna F. Haneef, Nikolas J. Podraza, Moses H. W. Chan, Venkatraman Gopalan, Karin M. Rabe, Roman Engel-Herbert. Correlated metals as transparent conductors. Nature Materials, 2015; DOI: 10.1038/nmat4493

25 COMMENTS

  1. I want to show some appreciation to you just for bailing me out of this particular difficulty. After surfing around throughout the the net and getting thoughts which are not pleasant, I figured my entire life was done. Being alive without the answers to the issues you’ve sorted out all through your main short post is a serious case, and those that would have negatively affected my career if I hadn’t discovered your site. Your personal mastery and kindness in playing with a lot of stuff was helpful. I’m not sure what I would’ve done if I hadn’t come across such a stuff like this. I can also now look forward to my future. Thanks a lot so much for your impressive and results-oriented guide. I won’t hesitate to recommend your web sites to any individual who needs and wants support about this subject.

  2. I precisely wanted to say thanks once more. I’m not certain what I would’ve sorted out without the actual methods contributed by you over that question. It previously was the horrifying issue for me, however , taking note of the professional strategy you resolved the issue took me to weep with gladness. I will be grateful for the help and pray you find out what a powerful job that you are putting in teaching men and women through your webpage. I am certain you’ve never come across any of us.

  3. I am only writing to make you be aware of of the impressive experience our princess had using the blog. She even learned many pieces, including what it is like to have a very effective giving spirit to get certain people without hassle know various complex issues. You actually exceeded readers’ expectations. Many thanks for showing the good, trusted, explanatory and unique tips about that topic to Gloria.

  4. I want to express my passion for your generosity for women who need assistance with the area. Your real commitment to getting the solution all through had been particularly good and has really empowered guys and women much like me to reach their goals. Your new warm and helpful advice can mean a lot a person like me and especially to my colleagues. Best wishes; from each one of us.

  5. I simply wanted to appreciate you once more. I do not know what I would’ve carried out in the absence of these smart ideas shown by you directly on this area of interest. It had become a very intimidating setting in my opinion, however , finding out a new professional technique you processed that took me to weep over contentment. Now i’m happy for your assistance as well as have high hopes you realize what a great job you happen to be undertaking educating many others thru your blog. I am sure you haven’t met all of us.

  6. Thanks so much for providing individuals with an extraordinarily wonderful possiblity to read from this blog. It’s usually very enjoyable plus full of a great time for me personally and my office fellow workers to search the blog nearly three times a week to read through the latest guides you have got. Not to mention, we are always astounded with the splendid tips you give. Some 4 ideas in this posting are particularly the most beneficial I have had.

  7. I am only writing to let you understand what a fabulous discovery my girl found checking your web page. She mastered numerous issues, not to mention how it is like to possess an awesome teaching mindset to make many people without hassle have an understanding of a number of complex topics. You actually did more than visitors’ desires. Thanks for giving such important, dependable, informative and also easy thoughts on this topic to Kate.

  8. I wanted to draft you one little bit of remark in order to thank you yet again with your beautiful tactics you have documented on this website. It’s certainly wonderfully generous of people like you to provide unreservedly all that a number of us could possibly have distributed for an e book to help with making some money for themselves, specifically seeing that you could have tried it in the event you desired. These techniques also worked to become good way to fully grasp many people have similar passion like my very own to see many more on the topic of this issue. I’m sure there are numerous more pleasant periods up front for individuals who scan your blog post.

  9. My husband and i have been really ecstatic when Albert could conclude his homework through the ideas he came across using your blog. It is now and again perplexing just to choose to be giving away solutions which often other folks could have been selling. So we see we’ve got the website owner to appreciate for that. All of the explanations you have made, the easy website navigation, the relationships you can assist to instill – it’s all overwhelming, and it is helping our son in addition to us know that the content is fun, and that’s tremendously important. Thanks for the whole lot!

  10. Thank you a lot for giving everyone an extremely breathtaking opportunity to read critical reviews from this site. It can be very kind and also packed with amusement for me personally and my office acquaintances to visit your web site really three times per week to see the newest secrets you have got. And indeed, I am also usually fulfilled considering the superb hints you serve. Some two facts in this posting are without a doubt the most effective I have ever had.

  11. I am glad for writing to let you know what a brilliant experience my cousin’s princess developed viewing your web site. She came to understand several pieces, most notably what it is like to possess an amazing coaching nature to let many more quite simply know just exactly several multifaceted things. You truly did more than people’s expected results. Thank you for producing the invaluable, trusted, revealing as well as fun thoughts on this topic to Emily.

  12. Thanks so much for giving everyone an exceptionally spectacular opportunity to read in detail from here. It really is so brilliant and as well , packed with amusement for me and my office colleagues to search your blog more than thrice in 7 days to learn the newest items you have got. And indeed, we are always satisfied with all the awesome methods served by you. Selected 1 ideas in this posting are undeniably the most beneficial I have had.

  13. My husband and i have been very ecstatic Raymond managed to finish off his analysis via the precious recommendations he came across while using the weblog. It is now and again perplexing just to choose to be making a gift of methods that some others could have been making money from. And we also recognize we need the writer to appreciate for that. All of the explanations you made, the simple web site menu, the friendships you can aid to engender – it’s got everything incredible, and it’s really helping our son in addition to us understand this theme is cool, which is very pressing. Many thanks for the whole thing!

  14. My husband and i got satisfied Chris could do his studies by way of the precious recommendations he came across when using the web page. It’s not at all simplistic to simply choose to be freely giving points that the rest could have been trying to sell. So we do know we now have the writer to thank for that. Those illustrations you’ve made, the simple website menu, the relationships you will aid to create – it is most spectacular, and it’s really leading our son and the family believe that this topic is fun, and that is exceedingly vital. Thank you for all!

  15. I have to express appreciation to this writer for bailing me out of this dilemma. After searching through the search engines and finding thoughts which were not helpful, I assumed my entire life was gone. Living devoid of the strategies to the issues you’ve solved as a result of the posting is a crucial case, and the ones which might have adversely damaged my career if I hadn’t noticed your blog. That capability and kindness in controlling all the stuff was excellent. I don’t know what I would have done if I hadn’t come across such a solution like this. It’s possible to at this point look forward to my future. Thank you so much for this reliable and result oriented guide. I will not think twice to refer the sites to anyone who requires direction on this area.

  16. I simply desired to appreciate you yet again. I do not know the things I might have gone through in the absence of these aspects documented by you about this area of interest. It seemed to be the challenging problem for me personally, nevertheless spending time with your expert form you processed the issue made me to weep for delight. Extremely thankful for your assistance as well as trust you know what an amazing job that you are getting into educating some other people using a web site. Most likely you have never encountered any of us.

  17. I and also my pals were found to be checking the great recommendations found on the blog and so quickly got a horrible suspicion I had not thanked the site owner for those tips. These young men appeared to be for that reason very interested to learn all of them and now have definitely been making the most of those things. Thanks for truly being simply accommodating and then for making a decision on this kind of terrific themes millions of individuals are really desperate to know about. My personal honest regret for not expressing appreciation to you earlier.

  18. I as well as my guys ended up reviewing the nice suggestions located on your web page and then immediately got an awful suspicion I had not thanked the blog owner for those secrets. All the women came joyful to read all of them and have now truly been taking advantage of them. Appreciation for truly being really helpful and also for pick out this kind of smart resources millions of individuals are really eager to discover. My personal sincere apologies for not saying thanks to you earlier.

  19. I must express my thanks to this writer for bailing me out of such a scenario. As a result of browsing throughout the internet and obtaining strategies that were not pleasant, I assumed my entire life was over. Existing devoid of the solutions to the issues you have sorted out through your good site is a critical case, and the ones that might have in a negative way affected my career if I had not discovered your blog. Your main talents and kindness in touching the whole thing was useful. I don’t know what I would’ve done if I hadn’t discovered such a solution like this. I can at this moment look forward to my future. Thanks for your time so much for the reliable and result oriented help. I won’t be reluctant to endorse your web sites to anyone who needs and wants assistance about this subject matter.

  20. I wanted to create you one little bit of remark so as to thank you the moment again for those splendid advice you’ve shown on this page. It’s quite unbelievably open-handed with you to offer unhampered all that many of us might have sold for an ebook to help with making some dough on their own, particularly considering that you might well have tried it if you wanted. The thoughts likewise acted to become great way to fully grasp that most people have the identical dream just like my personal own to realize way more in terms of this condition. Certainly there are many more pleasant instances in the future for individuals who find out your website.

  21. I wish to point out my admiration for your generosity giving support to men and women that need help with the topic. Your personal dedication to passing the solution all through turned out to be rather important and have continually encouraged employees much like me to achieve their objectives. Your entire helpful key points can mean a whole lot a person like me and substantially more to my peers. Thanks a ton; from each one of us.

  22. I definitely wanted to jot down a simple remark in order to express gratitude to you for all of the superb concepts you are giving at this site. My extensive internet investigation has finally been paid with reasonable tips to write about with my good friends. I ‘d believe that many of us visitors are definitely fortunate to live in a fabulous site with so many wonderful people with great guidelines. I feel truly grateful to have encountered the webpages and look forward to plenty of more awesome times reading here. Thanks a lot once more for everything.

  23. I actually wanted to make a quick comment to say thanks to you for some of the stunning secrets you are giving out at this website. My extensive internet investigation has at the end of the day been rewarded with wonderful facts to share with my guests. I would believe that we visitors actually are rather fortunate to be in a notable place with many awesome individuals with very helpful tactics. I feel truly privileged to have come across the webpages and look forward to so many more thrilling minutes reading here. Thanks a lot once more for a lot of things.

  24. My wife and i got very delighted when Jordan managed to deal with his investigations via the precious recommendations he discovered while using the web site. It’s not at all simplistic to simply continually be giving away points that men and women may have been selling. Therefore we understand we now have the website owner to be grateful to for that. The main illustrations you made, the straightforward blog menu, the relationships you make it easier to instill – it’s got most overwhelming, and it’s leading our son and us reckon that the idea is amusing, which is wonderfully pressing. Many thanks for all the pieces!

  25. I and also my pals have already been viewing the great suggestions located on your website then quickly I had a terrible suspicion I never thanked the site owner for those tips. My men ended up as a result happy to study all of them and already have in actuality been taking advantage of them. Appreciate your being really accommodating and then for utilizing such outstanding guides millions of individuals are really needing to understand about. My very own honest apologies for not saying thanks to you sooner.

LEAVE A REPLY