Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Think laterally to sidestep production problems

17.10.2017

Super thin photovoltaic devices underpin solar technology and gains in the efficiency of their production are therefore keenly sought. KAUST researchers have combined and rearranged different semiconductors to create so-called lateral p-n heterojunctions--a simpler process they hope will transform the fabrication of solar cells, self-powered nanoelectronics as well as ultrathin, transparent, flexible devices.

Two-dimensional semiconductor monolayers, such as graphene and transition-metal dichalcogenides like WSe2 and MoS2, have unique electrical and optical properties that make them potential alternatives to conventional silicon-based materials.


Solar power conversion using a lateral WSe2-MoS2­ heterojunction.

Credit: © 2017 WILEY VCH

Recent advances in material growth and transfer techniques have allowed scientists to manipulate these monolayers. Specifically, vertical stacking has led to ultrathin photovoltaic devices but requires multiple complex transfer steps. These steps are hampered by various issues, such as the formation of contaminants and defects at the monolayer interface, which limit device quality.

"Devices obtained using these transfer techniques are usually unstable and vary from sample to sample," says lead researcher and former visiting student of Associate Professor, Jr-Hau He, Meng-Lin Tsai, who adds that transfer-related contaminants significantly affect device reliability. Electronic properties have also proven difficult to control by vertical stacking.

To fully harness the exceptional properties of these two-dimensional materials, Tsai's team, under the mentorship of He, created monolayers featuring lateral WSe2-MoS2 heterojunctions and incorporated them into solar cells. Under simulated sunlight, the cells achieved greater power conversion efficiency than their vertically stacked equivalents.

To do this, first the researchers synthesized the heterojunctions by consecutively depositing WSe2 and MoS2 on a sapphire substrate. Next, they transferred the materials onto a silicon-based surface for photovoltaic device fabrication.

High-resolution microscopy revealed that the lateral junction displayed a clear separation between the semiconductors at the interface. Also, the researchers detected no discernable height difference between semiconductor regions, consistent with an atomically thin interface.

These interfacial characteristics signaled success. "Our structures are cleaner and more ideal than vertically stacked assemblies because we didn't need the multi-step transfer procedure," explains Tsai.

Furthermore, the lateral heterojunctions mostly retained their efficiency despite changes to the orientation of the incident light. Being able to take light coming from any direction means expensive solar tracking systems will become redundant.

According to Tsai, the implementation of lateral heterojunctions in more complex circuits and interconnects may result in higher performance than in conventional solar cells and so the team is working on the next steps. "We are trying to understand the underlying kinetics and thermodynamics of these heterojunctions to design more efficient cells," he adds.

Carolyn Unck | EurekAlert!

More articles from Materials Sciences:

nachricht Barely scratching the surface: A new way to make robust membranes
13.12.2018 | DOE/Argonne National Laboratory

nachricht Topological material switched off and on for the first time
11.12.2018 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>