Integrated OLED/OPV Planar “On-Chip” Refractometer

Brian Zacher, Alex Veneman Dan Huebner, Adam Simmonds, Neal R. Armstrong

Dept. of Chemistry, University of Arizona

Goal Statement

Integrate OLEDs and OPVs onto/into functionalized waveguide structures and perform spectroscopy.

-transition from bulky free space optical instrumentation to compact and inexpensive integrated device

www.bruker.com

Essence of Operation

• Forrest et. al., PRB, 58, 7,

3730-3740 (1998)

• Noda et. al., Organic

Electronics, 6, 3-9 (2005)

• McGehee et. al., J. Appl.

Phys., 97, (2005)

• Neyts, K., Applied Surface

Science, 244, 517-523,

(2005)

Significant Fractions of OLED Emission Are Lost into WG or “Substrate” Modes

-For OLED based “displays” this is inefficient……but

provides great potential for ATR spectroscopy!

Functions as described by Snell’s Law

Change in crit. angle =

Change in # photons reaching OPV

Critical Contributors of Technology and Inspiration For Organic Sensors

Meerholz, et. al., Adv. Mater., 20, 1966-1971 (2008).

Shinar(s), et. al., Analytica Chim Acta., 568, 190-199 (2006).

Bradley et. al., Lab Chip, 7, 58-63 (2007).

Ohmori et. al., IEEE Journal of Selected Topics in Quantum Electronics, 10,1, 70-78 (2004).

Integration of Light Sources and Detectors on a Single Chip

ATR/Waveguide

Element

OLED OPV OPV

Side View

Top View

OLED/OPV – Dual Beam ATR Photometer/Refractometer Platforms

gla

ss

ITO

C60

Al

Pc

BC

P CuPc/C60

TiOPc/C60

Small Molecule OLEDs and OPVs

ITO/PEDOT/TPD/Alq3/Mg:Ag

OLEDs

OPVs

OPV Short-Circuit Current as a Function of OLED Current

•0.002% external quantum efficiency

•1% OLED

•5% OPV

Experimental – Measure Refractive Index of Sucrose-Water Solution

•Sucrose-Water R.I. values published for 1E-5 resolutions

•~+1.6E-4 R.I. units per 0.1 wt.%

•Essentially zero absorbance of visible light (can ignore imaginary R.I. term)

Reference Cells

Sample Cells

Instrumentation

Key Features: o Battery Powered

o Mobile, low noise o OLED driven with pulsed

constant-current o Supports lock-in, thermal

o OPV monitored in short-circuit mode o Linear current response,

low shot noise o Integrated Lock-In amplifier

o Dual-Beam o Real-time baseline

Future Work

• Brighter OLEDs more efficient OPVs

• Integrate onto/into a single-mode waveguide

– 100 - 1000x increase in sensitivity

– Current device is ~80,000 mode

• Spectroscopy

– Narrow band light sources/detectors

– Multiple source/detector pairs on single substrate

Students/Collaborators/Research Support

Alex Veneman, Adam Simmonds, Dan Huebner, Erin Ratcliff

Contact me: Brian Zacher

bzacher@ email.arizona.edu 520 488 7261

Research support: National Science Foundation (CHE-0517963) NSF-STC CMDITR (DMR 0120967) Office of Naval Research