Details

Autor(en) / Beteiligte

• Lu, H
• Ho, S.-J
• Chen, H.-S
• Yang, A. C.-M

Titel

Interactions of Excited Charges with Substrate Fields in CdSe/ZnS Quantum Dots Embedded in Nano Polymer Films: Implications for Light-Emitting and Photovoltaic Devices

Ist Teil von

• ACS applied nano materials, 2021-02, Vol.4 (2), p.2108-2117

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Nanoparticles of quantum dots (QDs), thanks to their outstanding quantum efficiencies and size-tunable optical properties, are widely used in optoelectronic devices such as light-emitting diodes and photovoltaic cells. In applications, the QDs are often supported in nano polymer films and may be subjected to the electronic interactions with the heterojunction substrate fields that strongly influence the performance. We investigated these interactions by examining the photoluminescence (PL) of the core–shell QDs (CdSe/ZnS) embedded (1 wt %) in polymer films on either a narrow (Si-wafer) or wide (cover glass) band gap substrate (relative to the QD). We found that the QD particles tend to undergo depth segregation in the nano films, which generally showed with the depth distribution showing independence on the substrate choice. However, the PL as affected by the heterojunction interactions demonstrated a film thickness effect strikingly dependent on the substrate band gap size, revealing the operation of the heterojunction field. On the narrow band gap substrate of Si-wafer, the PL diminished quickly with the heterojunction field, suggestive of charge quenching via percolated pathways of the structured QDs within the matrix. Whereas, on the wide band gap cover glass that behaved as nonquenching substrate, the PL decreases with the field and was substantially limited by the QD nanoconfinement, indicating the dominance of exciton charge separation in the heterojunction interactions from increased exciton charge separation inflicted by the heterojunction exciton charge separation. The interactions were further examined by drastic alterations of the film morphology through dewetting, and the PL behaviors were found in good agreement with the unveiled dependences on the heterojunction fields and QD dispersion. The results bear important implications to QD optoelectronic applications.