Photoconductivity of PbSe quantum-dot solids: dependence on ligand anchor group and length.
The assembly of quantum dots is an essential step toward many of their potential applications. To form conductive solids from colloidal quantum dots, ligand exchange is required. Here we study the influence of ligand replacement on the photoconductivity of PbSe quantum-dot solids, using the time-resolved microwave conductivity technique. Bifunctional replacing ligands with amine, thiol, or carboxylic acid anchor groups of various lengths are used to assemble quantum solids via a layer-by-layer dip-coating method. We find that when the ligand lengths are the same, the charge carrier mobility is higher in quantum-dot solids with amine ligands, while in quantum-dot solids with thiol ligands the charge carrier lifetime is longer. If the anchor group is the same, the charge carrier mobility is ligand length dependent. The results show that the diffusion length of charge carriers can reach several hundred nanometers.
Optoelectronic Material Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL, Delft, The Netherlands.
Yunan
Y
Gao
Michiel
M
Aerts
C S Suchand
CS
Sandeep
Elise
E
Talgorn
Tom J
TJ
Savenije
Sachin
S
Kinge
Laurens D A
LD
Siebbeles
Arjan J
AJ
Houtepen
D004553:Electric Conductivity; D007854:Lead / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry* / Q000528:radiation effects*
D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead