Laser Patterning of Chalcopyrite and
Perovskite based Solar Cells:
Investigation of the Laser-Material Interaction
and Laser-induced Damages
vorgelegt von
M.Sc.
Christof Schultz
an der Fakultät IV - Elektrotechnik und Informatik
der Technischen Universität Berlin
zur Erlangung des akademischen Grades
Doktor der Ingenieurwissenschaften
-Dr.-Ing.-
genehmigte Dissertation
Promotionsausschuss:
Vorsitzender: Prof. Dr. Steve Albrecht
Gutachter: Prof. Dr. Bernd Szyszka
Gutachter: Prof. Dr. Bert Stegemann
Gutachter: Prof. Dr. Klaus Lips
Tag der wissenschaftlichen Aussprache: 16. Dezember 2020
Berlin 2021
Table of Contents
Abstract i
1 Introduction 1
2 Theory 7
2.1 Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.2 Laser-material interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.3 Manuscript: Laser patterning of thin-films . . . . . . . . . . . . . . . . . . 15
2.2 Solar cells - photo-electrical behavior and interconnection ............. 46
2.2.1 Absorption of light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.2.2 Charge carrier separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.2.3 Recombination .................................. 50
2.2.4 Photo-electrical properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
2.2.5 Monolithic series interconnection ....................... 56
2.3 Solar cells - preparation and material properties ................... 60
2.3.1 CIGSe solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.3.2 Perovskite solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table of Contents
3 Methods 79
3.1 Laser patterning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2 Simulation ......................................... 84
3.3 Measurement techniques ................................. 89
3.3.1 Optical microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.3.2 Laser-scanning microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.3.3 Atomic force microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.3.4 Scanning electron microscopy and energy dispersive x-ray spectroscopy . 90
3.3.5 Photoluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4 Sample Overview 99
5 Results and discussion 107
5.1
Manuscript: Laser-induced local phase transformation of CIGSe for monolithic
serial interconnection: Analysis of the material properties . . . . . . . . . . . . . 108
5.2 Manuscript: Revealing and Identifying Laser-Induced Damages in CIGSe Solar
Cells by Photoluminescence Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . 118
5.3
Manuscript: Enhanced Recombination Next to Laser-Patterned Lines in CIGSe
Solar Cells Revealed by Spectral and Time- resolved Photoluminescence . . . . . 128
5.4 Comprehensive calculation of the laser-induced heat flow . . . . . . . . . . . . . 136
5.5
Manuscript: Evidence of
PbI2
-Containing Debris Upon P2 Nano-second Laser
Patterning of Perovskite Solar Cells . . . . . . . . . . . . . . . . . . . . . . . . . . 140
5.6
Manuscript: Ablation mechanisms of nanosecond and picosecond laser scribing
for metal halide perovskite module interconnection – An experimental and
numerical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
5.7 Comprehensive PL investigation of the vicinities of the laser scribed trenches . . 160
5.8 Laser-material interaction models . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
TABLE OF CONTENTS
5.8.1 CIGSe solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
5.8.2 Perovskite solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
5.8.3 Application of the laser-material interaction model . . . . . . . . . . . . . 168
6 Summary and conclusion 172
A Bibliography 176
A.1 List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
A.2 List of figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
A.3 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
B Symbols, material constants, MATLAB code 211
B.1 Symbols and acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
B.2 Material constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
B.3 Code of the simulation model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
C Supplementary information 223
C.1 Manuscript contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
C.2 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
D Affirmation in lieu of oath 237
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