TY - JOUR
T1 - Comparison of performance and optoelectronic processes in ZnO and TiO 2 nanorod array-based hybrid solar cells
AU - Wu, Fan
AU - Qiao, Qiquan
AU - Bahrami, Behzad
AU - Chen, Ke
AU - Pathak, Rajesh
AU - Mabrouk, Sally
AU - Tong, Yanhua
AU - Li, Xiaoyi
AU - Zhang, Tiansheng
AU - Jian, Ronghua
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/10/31
Y1 - 2018/10/31
N2 - The reported efficiencies of pristine ZnO nanorod array (NRA)-based polymer-inorganic hybrid solar cells (HSCs) are normally lower than those of their pristine TiO 2 NRA-based counterparts. This difference typically results from the lower short-circuit current density (J sc ) of the ZnO NRA device. This paper presents a comparative study of pristine ZnO and TiO 2 NRA-based HSCs. We investigate the morphological structure (length, diameter, number density, area of nanorod laterals), photovoltaic performance (current density-voltage J–V, external quantum efficiency EQE), and optoelectronic processes related to electron transfer (electron mobility μ e , electron diffusion length L D , electron lifetime τ e and electron transit time τ t related electron collecting efficiency η cc , electron injection η inj , surface potential SP, photoluminescence PL, bound charge pairs BCP) in HSCs, with ZnO and TiO 2 NRA as electron acceptor. Our comparative investigations reveal that the factors relating to the interface area, μ e , L D , and η cc are not the key factors responsible for the difference in the value of J sc in ZnO and TiO 2 NRA-based HSCs with the same device structure. In fact, the crucial step for a lower J sc in ZnO NRA-based HSCs than in TiO 2 NRA-based HSCs is attributed to the less efficient transfer of photo-generated electrons at the charge separation interface in ZnO NRA-based HSCs. Dynamic characterizations indicate that the transfer of interfacial photo-generated electrons in TiO 2 NRA-based HSCs is more efficient than ZnO NRA-based HSCs, and is confirmed by Kelvin probe force microscopy (KPFM) and PL studies. The reason for the better interface charge transfer property in MEH-PPV/TiO 2 NRA than that of in MEH-PPV/ZnO NRA is further investigated by Marcus model, we find that more trapped BCP states are generated in the ZnO NRA based HSCs, which resulting in lower interfacial electron injection efficiency from polymer to ZnO NRA.
AB - The reported efficiencies of pristine ZnO nanorod array (NRA)-based polymer-inorganic hybrid solar cells (HSCs) are normally lower than those of their pristine TiO 2 NRA-based counterparts. This difference typically results from the lower short-circuit current density (J sc ) of the ZnO NRA device. This paper presents a comparative study of pristine ZnO and TiO 2 NRA-based HSCs. We investigate the morphological structure (length, diameter, number density, area of nanorod laterals), photovoltaic performance (current density-voltage J–V, external quantum efficiency EQE), and optoelectronic processes related to electron transfer (electron mobility μ e , electron diffusion length L D , electron lifetime τ e and electron transit time τ t related electron collecting efficiency η cc , electron injection η inj , surface potential SP, photoluminescence PL, bound charge pairs BCP) in HSCs, with ZnO and TiO 2 NRA as electron acceptor. Our comparative investigations reveal that the factors relating to the interface area, μ e , L D , and η cc are not the key factors responsible for the difference in the value of J sc in ZnO and TiO 2 NRA-based HSCs with the same device structure. In fact, the crucial step for a lower J sc in ZnO NRA-based HSCs than in TiO 2 NRA-based HSCs is attributed to the less efficient transfer of photo-generated electrons at the charge separation interface in ZnO NRA-based HSCs. Dynamic characterizations indicate that the transfer of interfacial photo-generated electrons in TiO 2 NRA-based HSCs is more efficient than ZnO NRA-based HSCs, and is confirmed by Kelvin probe force microscopy (KPFM) and PL studies. The reason for the better interface charge transfer property in MEH-PPV/TiO 2 NRA than that of in MEH-PPV/ZnO NRA is further investigated by Marcus model, we find that more trapped BCP states are generated in the ZnO NRA based HSCs, which resulting in lower interfacial electron injection efficiency from polymer to ZnO NRA.
KW - Hybrid semiconductor
KW - Nanorod array
KW - Optoelectronic processes
KW - Solar cells
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U2 - 10.1016/j.apsusc.2018.06.097
DO - 10.1016/j.apsusc.2018.06.097
M3 - Article
AN - SCOPUS:85058450702
SN - 0169-4332
VL - 456
SP - 124
EP - 132
JO - Applied Surface Science
JF - Applied Surface Science
ER -