Quantum-dot films multiply electrons, improve solar-energy harvesting

Delft, The Netherlands--Delft University of Technology (TU Delft) and Toyota Motor Europe (Brussels, Belgium) researchers have demonstrated that several mobile electrons can be produced by the absorption of a single light particle in films of coupled quantum dots, enabling quantum-dot solar cells with increased photon-to-electron conversion efficiency. The research is published in the October issue of Nano Letters.

The theoretical conversion efficiency of quantum-dot semiconductor solar cells is 44%. This is due to carrier multiplication in these quantum-dot nanoparticles. In conventional silicon-based photovoltaic (http://www.laserfocusworld.com/articles/print/volume-46/issue-8/features/photonic-frontiers.html) (PV) solar cells, an absorbed light particle excites one electron. But in a quantum-dot solar cell, a light particle can excite several electrons, multiplying the number of electrons and increasing the overall power conversion efficiency. 

Several years ago it was demonstrated that carrier multiplication is more efficient in quantum dots than in traditional semiconductors. As a result, quantum dots are being heavily investigated worldwide for use in solar cells.

A problem with using carrier multiplication is that the produced charges live only a very short time (around 0.00000000005 s) before they collide with each other and disappear through an Auger recombination decay process. However, the researchers have now demonstrated that even this very short time is long enough to separate the multiple electrons from each other. They prepared films of quantum dots in which the electrons can move so efficiently between the quantum dots that they become free and mobile before the time it takes to disappear via Auger recombination. In these films, up to 3.5 free electrons are created per absorbed light particle. In this way, these electrons do not only survive, they are able to move freely through the material for collection in a solar cell. 

SOURCE: TU Delft; http://home.tudelft.nl/en/current/latest-news/article/detail/drie-voor-de-prijs-van-een-mobiele-elektronen-vermenigvuldigd-in-kwantumdot-films/

IMAGE: The process of carrier multiplication in quantum-dot films enables an absorbed light particle to excite more than one electron, enhancing the conversion efficiency of quantum-dot-based solar cells. (Courtesy TU Delft)

The process of carrier multiplication in quantum-dot films enables an absorbed light particle to excite more than one electron, enhancing the conversion efficiency of quantum-dot-based solar cells

50 YEARS OF SOLID-STATE LASERS


A long way from the ruby laser

Most Popular Articles

Webcasts

Laser Measurements Critical to Successful Additive Manufacturing Processes

Maximizing the stability of the variables going into any manufacturing process is what ensures ts consistency and high quality. Specifically, when a laser is...

Ray Optics Simulations with COMSOL Multiphysics

The Ray Optics Module can be used to simulate electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the ...

Multichannel Spectroscopy: Technology and Applications

This webcast, sponsored by Hamamatsu, highlights some of the photonic technology used in spectroscopy, and the resulting applications.

Handheld Spectrometers

Spectroscopy is a powerful and versatile tool that traditionally often required a large and bulky instrument. The combination of compact optics and modern pa...
White Papers

Narrow-line fiber-coupled modules for DPAL pumping

A new series of fiber coupled diode laser modules optimized for DPAL pumping is presented, featur...

Accurate LED Source Modeling Using TracePro

Modern optical modeling programs allow product design engineers to create, analyze, and optimize ...

Optical Isolators Improve Engraving Performance of Pulsed Fiber Lasers

The deleterious effects of back reflections on pulsed fiber lasers used in marking and engraving ...
Technical Digests

ADHESIVES, SEALANTS, AND COATINGS: Solutions for optical technologies

A vast array of optical systems of various types and degrees of complexity require the use of adh...

WAVELENGTH-SWEPT LASERS: Dispersion-tuned fiber laser sweeps over a 140 nm range for OCT

By eliminating the use of mechanical tunable filters and instead tuning by intensity-modulation i...

Keeping pace with developments in photonic materials research

For demanding or custom spectroscopy solutions, care must be taken in selecting and integrating a...

HIGH-POWER FIBER LASERS: Working in the kilowatt regime

High-power materials-processing fiber lasers are available in an increasing variety of forms, as ...

Click here to have your products listed in the Laser Focus World Buyers Guide.
Social Activity
  •  
  •  
  •  
  •  
  •  
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS