This document summarizes research on plasmon-enhanced heterojunction solar cells made of PbS quantum dots and ZnO nanowires. The sizes and properties of the nanostructures were characterized using techniques like TEM, SEM, and spectroscopy. Solar cells were fabricated by spin coating PbS quantum dots on ZnO nanowires grown on ITO glass. Au nanoparticles were introduced to potentially enhance light absorption and carrier diffusion through plasmonic effects. Device performance is being studied by measuring the photocurrent and efficiency with different architectures and Au nanoparticle incorporations.

1. Plasmon Enhanced Heterojunction Solar Cell
GEN LONG, LEVINE CHING,MOSTAFA SADOQI, HUIZHONG XU
Department of Physics, St. John’s University, Jamaica NY 11439
Abstract
Research supported by St John’s University
Summary
 The hetero-junction solar cell made by PbS QDs and ZnO
NWs are fabricated and studied
 The effects of introduction of Au nanoparticles is under study
?Questions?
Please email Dr. Gen Long at
longg@stjohns.edu
Characterizations
TEM images shows the sizes of PbS QDs
Here we report an undergoing, systematic study of hetero-junction
solar cells made of colloidal quantum dots (PbS) and nanowires (ZnO)
on top of ITO glass, with/without metal nanoparticles (Au). The sizes
morphology, and band gaps of nanostructures were characterized by
TEM, SEM, and photospectrometer. The films made of nanostructured
hetero-junction of solar cell devices was characterized by AFM, SEM
and Raman spectrometer, etc. The effect on introducing metal
nanoparticles is still undergoing.
Background
 Colloidal quantum dots (QDs) provide convenient means for film
fabrication by simple spin coating and inexpensive alternative
approach to new solar cell materials
 PbS nanoparticles grown in solution have very low bandgap and
can absorb up to NIR wavelength
 ZnO Nanowires grown on ITO form a hetero-junction architechture
that increase light absorption bandwidth
 Introducing metal nanoparticles might further help with light
absorption, increase diffusion length, etc.
Solar Cell Device Fabrication
Plasmon Enhancement of Photocurrent and
Efficiency in the Heterojunction Solar Cell?
 Can introducing metal nanoparticles enhance the photocurrent
of quantum structures based heterojunction solar cell?
 It’s believed the metal nanoparticles can help with light
absorption and increase carrier diffusion length.
SEM shows the sizes of ZnO nanowires on ITO
 Synthesis of PbS nanoparticles
• Hot injection growth in solution, by PbO, Oleic Acid and TMS as
precursors
 Growth of ZnO nanowires in ITO glass
• by hydrothermal method in water
 Spin coating in air
• treated with 1% EDT in Acetonitrile
 Introducing Au nanoparticles
• of different sizes, at different layers in the solar cell
 Thermal Annealing in air for 30minutes
 Different architectures of hetero-junction solar cell
• Affect photocurrent and efficiency?
Solar Cell Device AFM Characterization
Solar Cell Device Raman Characterization
Ramam measurement on
 ZnO NWs on ITO glass
 Thin PbS Film
 Thick PbS Film
AFM on Thin PbS Film AFM on Thick PbS Film
AFM on Thick PbS Film, Zoom-in AFM on ZnO NWs on ITO