Surface modification of a ZnO electron-collecting layer using atomic layer deposition to fabricate high-performing inverted organic photovoltaics.
A ripple-structured ZnO film as the electron-collecting layer (ECL) of an inverted organic photovoltaic (OPV) was modified by atomic layer deposition (ALD) to add a ZnO thin layer. Depositing a thin ZnO layer by ALD on wet-chemically prepared ZnO significantly increased the short-circuit current (Jsc) of the OPV. The highest power conversion efficiency (PCE) of 7.96% with Jsc of 17.9 mA/cm2 was observed in the inverted OPV with a 2-nm-thick ALD-ZnO layer, which quenched electron-hole recombination at surface defects of ZnO ripples. Moreover, an ALD-ZnO layer thinner than 2 nm made the distribution of electrical conductivity on the ZnO surface more uniform, enhancing OPV performance. In contrast, a thicker ALD-ZnO layer (5 nm) made the two-dimensional distribution of electrical conductivity on the ZnO surface more heterogeneous, reducing the PCE. In addition, depositing an ALD-ZnO thin layer enhanced OPV stability and initial performance. We suggest that the ALD-ZnO layer thickness should be precisely controlled to fabricate high-performing OPVs.
Department of Chemistry, Sungkyunkwan University , Suwon, 440-746, South Korea.
Kwang-Dae
KD
Kim
Dong Chan
DC
Lim
Jinhee
J
Hu
Jung-Dae
JD
Kwon
Myung-Geun
MG
Jeong
Hyun Ook
HO
Seo
Joo Yul
JY
Lee
Ka-Young
KY
Jang
Jae-Hong
JH
Lim
Kyu Hwan
KH
Lee
Yongsoo
Y
Jeong
Young Dok
YD
Kim
Shinuk
S
Cho
D004566:Electrodes; D004583:Electrons; D012993:Solar Energy; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
D015034:Zinc Oxide