The influence of ligands passivation on strength of Fermi level pinning in the quantum dots interface

Authors
Namhee KwonSong, Seung HoJin, JunyoungKim, SeunghwanKim, KitaeHwang, Gyu WeonYi, YeonjinOh, Soong JuKoch, NorbertKim, Yong-HoonHwang, Do KyungPark, Soohyung
Issue Date
2024-08
Publisher
Elsevier BV
Citation
Applied Surface Science, v.664
Abstract
PbS quantum dots capped by ethanedithiol (PbS QD-EDT) and tetrabutylammonium iodide (PbS QD-TBAI) and supported by different substrates were examined in terms of Fermi level pinning (FLP), gap states, and electron and hole barriers (Φe and Φh, respectively) using ultraviolet and low-energy inverse photoemission spectroscopy. The former analysis showed that TBAI and EDT differed in their ability to induce gap-state passivation, with the corresponding energy difference determined as 4.0 eV. Two FLP regimes were identified: at substrate work function (Фsub) < 4.0 eV, both ligands showed perfect FLP (S ? 0 for holes and electrons), whereas at Фsub > 4.0 eV, the pinning strength of PbS QD-EDT (S of Фb,h and Фb,e = 0.19 and 0.24, respectively) exceeded that of PbS QD-TBAI (S of Фb,h and Фb,e = 0.53 and 0.57, respectively). Thus, the gap states were more effectively passivated in the case of PbS QD-TBAI. Our results indicate the importance of considering FLP strength when working with high-work-function substrates for the design of optimized QD-based devices.
Keywords
STATES; PHOTOTRANSISTORS; TRANSITION; VALENCE; GAP; SOLAR-CELLS; GRAPHENE; Energy level alignment; Photoemission spectroscopy; Low-energy inverse photoemission; spectroscopy; PbS quantum dot; Gap state; Fermi level pinning
ISSN
0169-4332
URI
https://pubs.kist.re.kr/handle/201004/149922
DOI
10.1016/j.apsusc.2024.160235
Appears in Collections:
KIST Article > 2024
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML

qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE