2026-09-19T01:49:07Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/278692022-01-13T07:54:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Vladimir Bulović.
Arango, Alexi Cosmos, 1975-
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2005-09-26T15:54:19Z
2005-09-26T15:54:19Z
2005
2005
http://hdl.handle.net/1721.1/27869
60678864
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 113-119).
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.
by Alexi Cosmos Arango.
S.M.
119 p.
2924451 bytes
3038308 bytes
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Massachusetts Institute of Technology
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http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
A quantum dot heterojunction photodetector
Thesis
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Publication
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<Abstract>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.</Abstract>
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