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

Most Popular Articles

Webcasts

Opportunities in the Mid-IR

The technology for exploiting the mid-IR is developing rapidly:  it includes quantum-cascade lasers and other sources, spectroscopic instruments of many...
White Papers

Introduction to scientific InGaAs FPA cameras

Working in the near infrared (NIR) and shortwave infrared (SWIR) regions of the spectrum offers r...
Technical Digests

OPTICAL COATINGS: Evolving technology produces new benefits

The antireflection, high-reflection, and/or spectral characteristics provided by optical coatings...

REMOTE FIBER-OPTIC SENSING: Data in abundance from difficult environments

The use of optical fibers to measure strain, temperature, and other parameters at desired points ...

SCANNERS FOR MATERIALS PROCESSING: Serving demanding applications

Galvanometer-based scanners are an essential component in laser-based materials-processing system...

Click here to have your products listed in the Laser Focus World Buyers Guide.

PRESS RELEASES

AFL Secures Patent for OTDR Technology

10/03/2013 AFL has been awarded a patent for “Optical Time Domain Reflectometer,” US Patent 8,411,259. The p...
Social Activity
  •  
  •  
  •  
  •  
  •  
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS