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The Role of Hydrogen from ALD‐Al 2 O 3 in Kesterite Cu 2 ZnSnS 4 Solar Cells: Grain Surface Passivation
Author(s) -
Park Jongsung,
Huang Jialiang,
Yun Jaesung,
Liu Fangyang,
Ouyang Zi,
Sun Heng,
Yan Chang,
Sun Kaiwen,
Kim Kyung,
Seidel Jan,
Chen Shiyou,
Green Martin A.,
Hao Xiaojing
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201701940
Subject(s) - kesterite , czts , passivation , materials science , atomic layer deposition , dangling bond , solar cell , chemical engineering , hydrogen , layer (electronics) , silicon , nanotechnology , optoelectronics , chemistry , organic chemistry , engineering
In this research, a new route of surface passivation is reported by introducing hydrogen from the atomic layer deposited (ALD) Al 2 O 3 layer into pure sulfide Cu 2 ZnSnS 4 (CZTS) solar cells. Different amounts of hydrogen are incorporated into the Cu 2 ZnSnS 4 /CdS interface through controlling the thickness of the ALD‐Al 2 O 3 layer. The device with three cycles of ALD‐Al 2 O 3 yields the highest efficiency of 8.08% (without antireflection coating) with improved open‐circuit voltage of up to 70 mV. With closer examination on the passivation route of ALD‐Al 2 O 3 , it is revealed by the surface chemisty study that the Al 2 O 3 can be etched away by ammonium hydroxide in the CdS buffer deposition process. Instead, the hydrogen is detected within a shallow depth from the CZTS surface, and makes a significant difference in the measured distribution of contact potential difference and device performance. This may be interpreted by the effect of hydrogen passivation of the CZTS surface by curing dangling bonds at the surface of CZTS grains. This work may provide a new direction of further improving the performance of kesterite solar cells.