IV Characterization of OLEDs Using the B2900A Series of SMUs

Introduction

Organic light emitting diodes (OLEDs) have been attracting a lot of attention recently, especially for use in flat panel televisions. This is due to several advantages they possess over cathode ray and liquid crystal technologies, including superior angled viewing, lack of need for a backlight and lower drive voltage and power consumption.

Much of the research into OLED technology centers around improving efficiency and extending the OLED’s lifetime. To properly evaluate OLED devices, a precise and broad range of current versus voltage (IV) measurement capabilities is required.

Keysight Technologies, Inc. B2901/02/11/12A Precision Source/Measure Unit is a compact and cost-effective bench-top Source/Measure Unit (SMU) with the capability to output and measure both voltage and current. The B2900A Series of SMUs enables you to make a wide range of current versus voltage (IV) measurements more accurately and quickly than ever before.

In addition, the B2900A Series of SMUs comes with an intuitive graphical user interface (GUI) and free PC-based application software that make it easy for you to begin making productive measurements immediately. These features make the B2900A Series of SMUs the best solution for accurate electrical characterization of OLEDs.

The B2900A Series of SMUs allows you to accurately and easily measure the basic IV parameters and characteristics of OLEDs, including forward and reverse bias IV characteristics as well as leakage current measurements.

What is the B2900A Series of SMUs?

An SMU combines the capabilities of a current source, a voltage source, a current meter and a voltage meter along with the capability to switch easily between these various functions into a single instrument. This gives it the ability to evaluate the IV characteristics of devices across all four measurement quadrants without the need for any additional equipment.

Besides being able to output and measure voltage or current very accurately, SMUs also possess a compliance feature that allows a limit to be placed on the voltage or current output to prevent device damage. The members of the B2900A Series of SMUs are single or dual channel SMU units that offer a wide range of IV measurement capability for a variety of two-terminal and three-terminal devices.

They cover currents from 10 fA to 3 A (DC)/10.5 A (pulse) and voltages from 100 nV to 210 V. In addition to their DC operation mode, the B2900A Series of SMUs also has the ability to perform pulsed measurements in order to prevent device self-heating from distorting the measurement results.

The B2900A Series of SMUs supports 4-wire measurements (remote sensing) to eliminate the voltage error caused by test lead residual resistance. Measurements made through a 2-wire connection can contain significant error when the resistance being measured is comparable to that of the test leads (please see Figure 2a).

However, a 4-wire measurement uses one pair of leads to force current and the other pair of leads to monitor voltage. This eliminates cable resistance effects so that only the voltage drop across the DUT is measured (please see Figure 2b).

In addition, the 4-wire measurement scheme of the B2900A Series of SMUs keeps the voltage between the sense points (A and B in Figure 2b) at exactly the specified voltage Vset, thereby ensuring that your device is characterized exactly under the measurement conditions you specify.

Quick and easy IV characterization

During routine device evaluation it is often desirable to make a quick measurement from the instrument’s front panel without having to go through the time and trouble of writing a test program. To meet this need, all members of the B2900A Series of SMUs have a resident GUI that makes it easy to perform a variety of tests and save measurement data without having to write any code.

The wide QVGA LCD display of the B2900A Series of SMUs supports an easy-to-use GUI that provides easy instrument control from the front panel (please see Figure 3). The GUI of the B2900A Series of SMUs has the following multiple viewing modes: Single View, Dual View, Graph View and Roll View (for viewing time domain measurements).

Single View mode allows you to easily set up not only constant voltage and current measurements but also swept voltage and current measurements. Dual View can perform similar functions for both channels simultaneously (for B2902A and B2912A).

After measurement completion you can use the front panel GUI to graphically view measurement results such as IV curves using Graph View, and display a list of the measurement data using the Measure Result dialog window.

The B2900A Series of SMUs has a USB interface on the front panel so that a USB flash memory device can be used with the B2900A Series of SMUs to save and load measurement setups as well as to save measurement results. In addition, Graph View supports a Screen Dump function that enables you to save screen images (such as IV curves) to any attached USB flash memory device as JPEG files, making it easy to include graphical results in reports and presentations.

Ready-to-use PC software

In addition to its powerful and easy-to-use GUI, the B2900A Series of SMUs comes with free PC application software to facilitate program development if you prefer PC-based instrument control. The Keysight B2900A Graphical Web Interface and the Keysight B2900A Quick I/V Measurement Software are both available for the B2900A Series of SMUs.

The Keysight B2900A Graphical Web Interface provides functionality to allow access to the B2900A Series of SMUs over a LAN connection. The B2900A Series of SMUs is fully compliant with the LXI class C specification and it contains a web server that provides a webpage with an interface to support the basic measurement functions of the B2900A Series of SMUs.

You can quickly and easily make measurements using a standard web browser by just connecting the B2900A Series of SMUs to a PC using a LAN cable.