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Influence of ligand exchange on the electrical transport properties of PbS nanocrystals
Author(s) -
Borriello Carmela,
Miscioscia Riccardo,
Mansour Shehab A.,
Di Luccio Tiziana,
Bruno Annalisa,
Loffredo Fausta,
Villani Fulvia,
Minarini Carla
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201532470
Subject(s) - ambipolar diffusion , materials science , nanocrystal , annealing (glass) , nanotechnology , transistor , field effect transistor , charge carrier , chemical engineering , optoelectronics , electrical engineering , composite material , physics , plasma , engineering , quantum mechanics , voltage
In this work, FETs are used as a research tool to study charge carrier mobilities in PbS nanocrystals (NCs) thin‐films employed as semiconducting layer in bottom‐gate bottom‐contact (BGBC) field‐effect transistors (FETs). The as‐synthesised NCs are surrounded by long alkyl chain ligands which act as electrical insulators. Therefore, a ligand exchange process with shorter molecules is necessary to enhance the free charges generation and transport. We used two different ligands: 1,2 ethandithiol (EDT) and 1,2,3,4‐tetrabutylammonium iodide (TBAI) and studied the charge mobility of PbS NCs comparing the electrical characteristics of FETs made by exchanged NCs. We analysed also the contemporary presence of both exchanged nanocrystals on the device. All the transistors showed p‐type transport behaviour, enhanced by an annealing process at 100 °C for 10 min. After this, only the TBAI‐treated NCs devices showed a n‐type transport, resulting in an ambipolar behaviour. Inkjet printing deposition techniques was also successfully used to deposit PbS‐(TBAI) NCs and ambipolar devices were obtained. In addition, for printed devices it was found that it is possible to modulate the charge transport properties by applying surface treatment to the substrate with a pentafluorothiophenol (PFTP). Indeed in this case, the p‐type transport was suppressed while n‐type behaviour was induced.