Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Riddle of missing efficiency in zinc oxide-based dye-sensitised solar cells solved

Illustration of the initial charge transfer step in a dye sensitized solar cell. A photon from the sun is absorbed and excites the dye molecule. Subsequently, an electron can is injected into the ZnO-Layer where it can be trapped by so called interface-states.
CREDIT: HZB/Mario Borgwardt
Illustration of the initial charge transfer step in a dye sensitized solar cell. A photon from the sun is absorbed and excites the dye molecule. Subsequently, an electron can is injected into the ZnO-Layer where it can be trapped by so called interface-states.

CREDIT: HZB/Mario Borgwardt

Abstract:
This explains why zinc-oxide (ZnO) dye-sensitised solar cells have not yet met expectations. The results evolved from collaboration between Monash University (Australia) and Joint Lab partners Helmholtz Zentrum Berlin (HZB) and the Freie Universität Berlin (FU Berlin). They have now been published online by Nature in the open access magazine Scientific Reports.

Riddle of missing efficiency in zinc oxide-based dye-sensitised solar cells solved

Berlin, Germany | Posted on April 15th, 2016

Converting the energy of the sun into electricity and solar hydrogen can be achieved with a whole series of materials. One important class of organic solar cells uses dyes applied to a semiconductor material like titanium dioxide (TiO2), for example. The dye molecules function as a kind of "translator" for the solar energy. They capture the light and inject electrons as free charges carriers into the TiO2 resulting in current flow. However, TiO2 is far from ideal and zinc oxide (ZnO) should actually be more suitable as an electrode material. This is because the charge carriers are far more mobile in ZnO, so they should flow more quickly after charge separation has occurred. In addition, nanostructures that capture sunlight especially efficiently can be produced in simple fashion using ZnO.

Detailed investigation of excited states with ultrashort Laser pulses

Nevertheless, constructing ZnO solar cells that better those of TiO2 had not been accomplished thus far. Now a team headed by Emad Aziz has for the first time directly observed the cause for this and investigated it in detail at the "Joint Ultrafast Dynamics Lab in Solutions and at Interfaces". The Joint Lab is being operated by HZB together with FU Berlin. It has a complete array of state-of-the-art laser instruments at its disposal, including a time-resolved photoelectron spectrometer that can generate ultra-short XUV pulses with duration below 45 femtoseconds. These ultra-short light pulses enable the temporal as well as energetic development of excited states to be tracked on ultra-short timescales.

Interface states as traps for charge carriers

"Our measurements show directly for the first time that charge carriers are temporarily trapped by formation of an interface state between the dye and the semiconductor boundary layer. As a result, they are no longer immediately available as free charge carriers", explains Mario Borgwardt, doctoral student on Aziz' team. These "trapped" electrons within the interface stay put longer. This increases the probability that they are "lost" again through recombination. That in turn reduces the efficiency level of the solar cell.

The samples for the experiment were made available by Prof. Leone Spiccia's team from Monash University, Australia. A fruitful collaboration evolved in the course of Spiccia's visit last year as part of his Helmholtz International Fellowship award from the Helmholtz Association that has contributed in a fundamental manner to the success of this project.

Helpful hints for the design of materials for energy conversion or storage

Aziz explains the importance of the results: "The work has led to a better understanding of the processes at the boundary layer between dye molecule and semiconductor. We have therefore been able to understand how dye and semiconductor materials communicate with one another. This enables us now to devise approaches for improving the communication in a direct way. That is important not only for the design of dye-sensitised solar cells, but also in order to be able to develop systems of materials for photocatalytic generation of hydrogen for storing solar energy as hydrogen fuel."

####

For more information, please click here

Contacts:
Prof. Dr. Emad Aziz

49-308-062-15003

Copyright © Helmholtz-Zentrum Berlin für Materialien und Energie (HZB)

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

The results are published in Scientific Reports 6, Article number: 24422 (2016), doi:10.1038/srep24422 Charge Transfer Dynamics at Dye-Sensitized ZnO and TiO2 Interfaces Studied by Ultrafast XUV Photoelectron Spectroscopy. Mario Borgwardt, Martin Wilke, Thorsten Kampen, Sven Mähl, Manda Xiao, Leone Spiccia, Kathrin M. Lange, Igor Yu. Kiyan & Emad F. Aziz:

Related News Press

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Possible Futures

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Materials/Metamaterials/Magnetoresistance

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Energy

Development of zinc oxide nanopagoda array photoelectrode: photoelectrochemical water-splitting hydrogen production January 12th, 2024

Shedding light on unique conduction mechanisms in a new type of perovskite oxide November 17th, 2023

Inverted perovskite solar cell breaks 25% efficiency record: Researchers improve cell efficiency using a combination of molecules to address different November 17th, 2023

The efficient perovskite cells with a structured anti-reflective layer – another step towards commercialization on a wider scale October 6th, 2023

Solar/Photovoltaic

Development of zinc oxide nanopagoda array photoelectrode: photoelectrochemical water-splitting hydrogen production January 12th, 2024

Shedding light on unique conduction mechanisms in a new type of perovskite oxide November 17th, 2023

Inverted perovskite solar cell breaks 25% efficiency record: Researchers improve cell efficiency using a combination of molecules to address different November 17th, 2023

Charged “molecular beasts” the basis for new compounds: Researchers at Leipzig University use “aggressive” fragments of molecular ions for chemical synthesis November 3rd, 2023

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project