Cheng-Ying Chen1,I-Jui Hsieh2,Pochun Chen2
National Taiwan Ocean University1,National Taipei University of Technology2
Cheng-Ying Chen1,I-Jui Hsieh2,Pochun Chen2
National Taiwan Ocean University1,National Taipei University of Technology2
In this work, atomic layer deposition (ALD) is conducted for growing Wide Bandgap Metal Oxides (ZnSnO) as buffer layers on p-type selenium (Se) absorbers, which was used in the first solid-state solar cell in 1883 and has a high absorption coefficient and mobility, making it a p-type absorber for wide energy gap (~1.8~2.0 eV) thin film solar cells. In addition, direct bandgap, earth-abundance, simple composition, non-toxicity, low melting point and environmental stability make Se inexpensive and developable for solar cells. However, in the n-type buffer layer perspective, so far, has not been found a suitable buffer layer for modulating conduction band offset (CBO) between n-type buffer layers and p-type Se absorbers.<br/>The benefit for using ALD growth ZnSnO can be summarized the as following points: (1) ZnSnO is wide band gap material (~3.2eV); (2) Controllable of Zn and Sn ratio, which can intentionally modulate the CBO become spike type (i.e., 0<CBO<0.5 eV); (3) ALD can effectively growth larger scale of thin-film and precisely control the thickness. Finally, the result presented the Zn<sub>1-x</sub>Sn<sub>x</sub>O (x=7%) under the optimization of ZnO and SnO ratio, the power conversion efficiency can be achieved at about 2.68%.