TY - JOUR

T1 - Fast, Infrared-Active Optical Transistors Based on Dye-Sensitized CdSe Nanocrystals

AU - Kumar, Krishan

AU - Liu, Quan

AU - Hiller, Jonas

AU - Schedel, Christine

AU - Maier, Andre

AU - Meixner, Alfred

AU - Braun, Kai

AU - Lauth, Jannika

AU - Scheele, Marcus

N1 - Funding information: The authors acknowledge the DFG for support under Grant SCHE1905/3 and under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD (EXC 2122, Project ID 390833453). The time-resolved photocurrent measurements have been funded by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 802822).

PY - 2019/12/26

Y1 - 2019/12/26

N2 - We report an optically gated transistor composed of CdSe nanocrystals (NCs), sensitized with the dye zinc β-tetraaminophthalocyanine for operation in the first telecom window. This device shows a high ON/OFF ratio of 6 orders of magnitude in the red spectral region and an unprecedented 4.5 orders of magnitude at 847 nm. By transient absorption spectroscopy, we reveal that this unexpected infrared sensitivity is due to electron transfer from the dye to the CdSe NCs within 5 ps. We show by time-resolved photocurrent measurements that this enables fast rise times during near-infrared optical gating of 47 ± 11 ns. Electronic coupling and accelerated nonradiative recombination of charge carriers at the interface between the dye and the CdSe NCs are further corroborated by steady-state and time-resolved photoluminescence measurements. Field-effect transistor measurements indicate that the increase in photocurrent upon laser illumination is mainly due to the increase in the carrier concentration while the mobility remains unchanged. Our results illustrate that organic dyes as ligands for NCs invoke new optoelectronic functionalities, such as fast optical gating at sub-bandgap optical excitation energies.

AB - We report an optically gated transistor composed of CdSe nanocrystals (NCs), sensitized with the dye zinc β-tetraaminophthalocyanine for operation in the first telecom window. This device shows a high ON/OFF ratio of 6 orders of magnitude in the red spectral region and an unprecedented 4.5 orders of magnitude at 847 nm. By transient absorption spectroscopy, we reveal that this unexpected infrared sensitivity is due to electron transfer from the dye to the CdSe NCs within 5 ps. We show by time-resolved photocurrent measurements that this enables fast rise times during near-infrared optical gating of 47 ± 11 ns. Electronic coupling and accelerated nonradiative recombination of charge carriers at the interface between the dye and the CdSe NCs are further corroborated by steady-state and time-resolved photoluminescence measurements. Field-effect transistor measurements indicate that the increase in photocurrent upon laser illumination is mainly due to the increase in the carrier concentration while the mobility remains unchanged. Our results illustrate that organic dyes as ligands for NCs invoke new optoelectronic functionalities, such as fast optical gating at sub-bandgap optical excitation energies.

KW - fluorescence lifetimes

KW - nanocrystals

KW - optical transistor

KW - organic dyes

KW - time-resolved photocurrent

KW - transient absorption spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=85076751176&partnerID=8YFLogxK

U2 - 10.1021/acsami.9b18236

DO - 10.1021/acsami.9b18236

M3 - Article

C2 - 31778068

AN - SCOPUS:85076751176

VL - 11

SP - 48271

EP - 48280

JO - ACS Applied Materials and Interfaces

JF - ACS Applied Materials and Interfaces

SN - 1944-8244

IS - 51

ER -