A quantum dot heterojunction photodetector

This thesis presents a new device architecture for photodetectors utilizing colloidally grown quantum dots as the principle photo-active component. We implement a thin film of cadmium selenide (CdSe) quantum dot sensitizers, sandwiched between an electron-transporting titanium dioxide (TiO2) layer and a hole-transporting N,N' diphenyl-N,N' bis(3-ethylphenyl)-(1,1'-biphenyl)- 4,4'-diamine (TPD) organic small molecule layer. The wide band gap TiO2 and TPD layers are found to block charge injection under reverse bias, yet serve as transport layers for photo-excited charge generated in the CdSe. The internal quantum efficiency is approximately 1% at zero bias and saturates at 3% at -1V. Current-voltage sweeps yield low dark current in reverse bias and significant hysteresis under illumination. We speculate that the hysteresis and low quantum efficiency are due to charge accumulation at the TiO2/CdSe interface.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Arango, Alexi Cosmos, 1975-

Advisor dc:contributor.advisor

• Vladimir Bulović.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/27869

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/27869