IEC TR 60747-5-12:2021

IEC TR 60747-5-12 ®
Edition 1.0 2021-10
TECHNICAL
REPORT
colour
inside
Semiconductor devices –
Part 5-12: Optoelectronic devices – Light emitting diodes – Test method of LED
efficiencies
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TR 60747-5-12 ®
Edition 1.0 2021-10
TECHNICAL
REPORT
colour
inside
Semiconductor devices –
Part 5-12: Optoelectronic devices – Light emitting diodes – Test method of LED

efficiencies
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.080.99 ISBN 978-2-8322-1035-9

– 2 – IEC TR 60747-5-12:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative reference . 8
3 Terms and definitions . 8
3.1 General terms and definitions . 9
3.2 Terms and definitions relating to the optoelectronic efficiencies . 9
3.3 Terms and definitions relating to measuring the efficiencies . 11
3.4 Terms and definitions relating to measuring current components . 12
3.5 Abbreviated terms . 12
4 LED efficiencies. 13
4.1 General . 13
4.2 Theoretical background of optoelectronic efficiencies . 15
4.3 Separate measurement of various efficiencies . 20
4.4 Requirements for accurate and reliable IQE measurement . 20
4.5 Classification of IQE measurement methods . 21
5 Conventional IQE measurement methods: features and limitations . 22
5.1 Calculation of the LEE . 22
5.2 Temperature-dependent photoluminescence (TDPL) . 22
5.3 Intensity-dependent photoluminescence (IDPL) or simply photoluminescence
(PL) . 23
5.4 Temperature-dependent time-resolved photoluminescence (TD-TRPL) . 26
5.5 Time-resolved photoluminescence (TRPL) . 28
5.6 Time-resolved electroluminescence (TREL) . 34
5.7 Constant ABC model . 39
5.8 Constant AB model . 45
6 Standard IQE measurement method I: TDEL . 46
6.1 Temperature-dependent electroluminescence (TDEL) method . 46
6.2 Temperature-dependent radiant power . 46
6.3 Evaluation of the IQE . 47
6.4 Validity of the TDEL: examples of blue LEDs . 49
6.5 Sequence of IQE determination by the TDEL . 50
6.6 Summary of the TDEL . 51
7 Standard IQE measurement method II: RTRM . 51
7.1 Room-temperature reference-point method (RTRM) . 51
7.2 Recombination coefficients, A, B, and C in semiconductors . 52
7.3 Strategy of the IQE measurement just at an operating temperature . 53
7.4 Theoretical background of the RTRM . 54
7.5 Example of the RTRM . 56
7.6 Comparison of IQEs by the TDEL and the RTRM . 59
7.7 Summary of the RTRM . 60
8 The RTRM versus the TDEL and the constant ABC model: comparisons . 60
9 LED performance issues related to the IQE measurement . 67
9.1 Various LED efficiency measurement . 67
9.2 Radiative and nonradiative currents . 70
9.3 The active efficiency (AE): IQE versus forward voltage . 74

10 Conclusion: test method of optoelectronic efficiencies of LEDs . 80
Bibliography . 81

Figure 1 – Sequence of the efficiency measurements . 20
Figure 2 – Theoretical model for analysing the TRPL experiment . 30
Figure 3 – Schematic TRPL response and its interpretation in terms of various lifetimes . 32
Figure 4 – Temporal responses of the TRPL for three samples . 33
Figure 5 – Fitted results of the measured TRPL response . 34
Figure 6 – Schematic diagram of the pulse current injection. 35
Figure 7 – Square of 1τ as a function of current density for a bias voltage . 39
EL
Figure 8 – Estimated IQE (left axis) and measured EQE (right axis) versus current
density . 39
Figure 9 – Experimental EQE curve of a blue LED . 42
Figure 10 – Normalized EQE curves (solid lines) and experimental data (rectangular
symbols) for different IQE peak values as a parameter for a blue LED emitting at
460 nm . 42
Figure 11 – SRH nonradiative carrier lifetime as a function of the C
τA= 1
( )
SRH
coefficient calculated from Equation (82) . 43
Figure 12 – Experimental EQE curve of a blue LED . 43
Figure 13 – Temperature characteristics of an LED . 47
Figure 14 – IQEs as a function of current at various operating temperatures from room
to cryogenic measured by the TDEL method . 49
Figure 15 – Two different cases of normalized EQE curves as a function of current at
various temperatures . 50
Figure 16 – Sequence of the IQE measurement by the TDEL method . 51
Figure 17 – Comparison between the conventional ABC model and the improved AB
model . 54
Figure 18 – Calculation procedure from a relative EQE curve to an IQE curve with the
RTRM . 54
Figure 19 – IQE calculation procedure as a function of current based on the RTRM. 57
Figure 20 – Example of the IQE calculation based on the RTRM . 59
Figure 21 – Comparison of the IQEs evaluated by (a) the TDEL and (b) the RTRM . 60
Figure 22 – Radiant power versus current of a blue LED sample measured at various
temperatures . 61
Figure 23 – Normalized intensities on linear and log scales measured at various
temperatures . 62
Figure 24 – I-V characteristics at various temperatures . 63
Figure 25 – Calculated a as a function of current for various temperatures. I at
2 ref
300 K is the current giving the minimum value of a in region II. . 64
Figure 26 – IQEs obtained by the RTRM (symbols) and the TDEL (solid lines) at
various temperatures . 64
Figure 27 – Comparison of the IE obtained from a at 300 K (left axis) and the
theoretical IE for constant I (right axis) . 65
leak
Figure 28 – Normalized EQE and the fitting by the constant ABC model . 66
Figure 29 – Ratio of the SRH, radiative, Auger recombination currents to the total
current . 66

– 4 – IEC TR 60747-5-12:2021 © IEC 2021
Figure 30 – Radiant power and forward voltage as a function of forward current . 68
Figure 31 – Calculation of the mean photon energy from the emission spectra . 69
Figure 32 – LED efficiencies as a function of forward current . 70
Figure 33 – Sequence of the radiative and nonradiative current measurements . 72
Figure 34 – IQE and forward voltage as a function of forward current . 72
Figure 35 – Radiative current and forward voltage as a function of forward current . 73
Figure 36 – Nonradiative current and forward voltage as a function of forward current . 73
Figure 37 – Total forward current, radiative current, and nonradiative current plotted as
a function of forward voltage . 74
Figure 38 – Distribution of the IQE and V for 31 blue MQW LEDs . 76
F
Figure 39 – Optoelectronic characteristics of three samples under consideration . 77
Figure 40 – Separated radiative and nonradiative current densities of samples 1 and 2 . 78
Figure 41 – Separated radiative and nonra
...