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ZnO@SnO2 engineered composite photoanodes for dye sensitized solar cells.

Milan R, Selopal GS, Epifani M, Natile MM, Sberveglieri G, Vomiero A, Concina I - Sci Rep (2015)

Bottom Line: Bi-oxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO2 (1.20%) and ZnO (1.03%).Synergistic cooperation is effective for both open circuit voltage and photocurrent density: enhanced values were indeed recorded for the layered photoanode as compared with bare oxides (Voc enhanced from 0.39 V in case of bare SnO2 to 0.60 V and Jsc improved from 2.58 mA/cm(2) pertaining to single ZnO to 14.8 mA/cm(2)).Compared with previously reported results, this study testifies how a simple electrode design is powerful in enhancing the functional performances of the final device.

View Article: PubMed Central - PubMed

Affiliation: Department of Information Engineering, University of Brescia - via Valotti 9, 25133 Brescia, Italy.

ABSTRACT
Layered multi-oxide concept was applied for fabrication of photoanodes for dye-sensitized solar cells based on ZnO and SnO2, capitalizing on the beneficial properties of each oxide. The effect of different combinations of ZnO@SnO2 layers was investigated, aimed at exploiting the high carrier mobility provided by the ZnO and the higher stability under UV irradiation pledged by SnO2. Bi-oxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO2 (1.20%) and ZnO (1.03%). Synergistic cooperation is effective for both open circuit voltage and photocurrent density: enhanced values were indeed recorded for the layered photoanode as compared with bare oxides (Voc enhanced from 0.39 V in case of bare SnO2 to 0.60 V and Jsc improved from 2.58 mA/cm(2) pertaining to single ZnO to 14.8 mA/cm(2)). Improved functional performances of the layered network were ascribable to the optimization of both high chemical capacitance (provided by the SnO2) and low recombination resistance (guaranteed by ZnO) and inhibition of back electron transfer from the SnO2 conduction band to the oxidized species of the electrolyte. Compared with previously reported results, this study testifies how a simple electrode design is powerful in enhancing the functional performances of the final device.

No MeSH data available.


(a) Effect of configuration of layered structure of ZnO@SnO2 network on dye loading as a function sensitization time (black circles: 1@5, pink squares: 1@4 and blue upper triangles: 3@3). (b) PCE vs dye loading based on data in Table 2, merged in a single graph, irrespective of the structure of the photoanode. The solid line is the linear fitting of the experimental data. (c) to (f) Functional parameters of the DSSCs as a function of their structure and sensitization time: Voc (c); Jsc (d); FF (e); PCE (f).
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f5: (a) Effect of configuration of layered structure of ZnO@SnO2 network on dye loading as a function sensitization time (black circles: 1@5, pink squares: 1@4 and blue upper triangles: 3@3). (b) PCE vs dye loading based on data in Table 2, merged in a single graph, irrespective of the structure of the photoanode. The solid line is the linear fitting of the experimental data. (c) to (f) Functional parameters of the DSSCs as a function of their structure and sensitization time: Voc (c); Jsc (d); FF (e); PCE (f).

Mentions: Three different layered architectures of ZnO@SnO2 (1@5, 2@4, 3@3) were thus sensitized for 2 h, 4 h, 6 h and 10 h. All the tested devices, irrespective of the photoanode architecture, showed best functional performances when sensitized for 6 h (see Table 2). One of the motivations behind this result is the maximized dye loading after 6 h sensitization, as clearly shown in Fig. 5b, in which PCE is reported as a function of dye loading, merging data coming from different photoanode structure and sensitization time. It is quite worth noting that PCE linearly increases with the increased dye uptake, and data from different photoanodes and different sensitization time are homogeneously distributed according to the linear PCE increase. The main functional parameter leading to increased PCE is Jsc, which well correlates with increased dye uptake. In fact, typical increase in Jsc occurs in DSSCs as a consequence of the increased optical density of the photoanode29, which enhances the amount of photogenerated charge, with minor effect on Voc. We can further observe that the 1@5 sample exhibits the highest dye uptake, compared to 2@4 and 3@3 (Fig. 5a), most probably because the SnO2 layer has much higher specific surface, compared to ZnO, according to SEM observations.


ZnO@SnO2 engineered composite photoanodes for dye sensitized solar cells.

Milan R, Selopal GS, Epifani M, Natile MM, Sberveglieri G, Vomiero A, Concina I - Sci Rep (2015)

(a) Effect of configuration of layered structure of ZnO@SnO2 network on dye loading as a function sensitization time (black circles: 1@5, pink squares: 1@4 and blue upper triangles: 3@3). (b) PCE vs dye loading based on data in Table 2, merged in a single graph, irrespective of the structure of the photoanode. The solid line is the linear fitting of the experimental data. (c) to (f) Functional parameters of the DSSCs as a function of their structure and sensitization time: Voc (c); Jsc (d); FF (e); PCE (f).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588567&req=5

f5: (a) Effect of configuration of layered structure of ZnO@SnO2 network on dye loading as a function sensitization time (black circles: 1@5, pink squares: 1@4 and blue upper triangles: 3@3). (b) PCE vs dye loading based on data in Table 2, merged in a single graph, irrespective of the structure of the photoanode. The solid line is the linear fitting of the experimental data. (c) to (f) Functional parameters of the DSSCs as a function of their structure and sensitization time: Voc (c); Jsc (d); FF (e); PCE (f).
Mentions: Three different layered architectures of ZnO@SnO2 (1@5, 2@4, 3@3) were thus sensitized for 2 h, 4 h, 6 h and 10 h. All the tested devices, irrespective of the photoanode architecture, showed best functional performances when sensitized for 6 h (see Table 2). One of the motivations behind this result is the maximized dye loading after 6 h sensitization, as clearly shown in Fig. 5b, in which PCE is reported as a function of dye loading, merging data coming from different photoanode structure and sensitization time. It is quite worth noting that PCE linearly increases with the increased dye uptake, and data from different photoanodes and different sensitization time are homogeneously distributed according to the linear PCE increase. The main functional parameter leading to increased PCE is Jsc, which well correlates with increased dye uptake. In fact, typical increase in Jsc occurs in DSSCs as a consequence of the increased optical density of the photoanode29, which enhances the amount of photogenerated charge, with minor effect on Voc. We can further observe that the 1@5 sample exhibits the highest dye uptake, compared to 2@4 and 3@3 (Fig. 5a), most probably because the SnO2 layer has much higher specific surface, compared to ZnO, according to SEM observations.

Bottom Line: Bi-oxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO2 (1.20%) and ZnO (1.03%).Synergistic cooperation is effective for both open circuit voltage and photocurrent density: enhanced values were indeed recorded for the layered photoanode as compared with bare oxides (Voc enhanced from 0.39 V in case of bare SnO2 to 0.60 V and Jsc improved from 2.58 mA/cm(2) pertaining to single ZnO to 14.8 mA/cm(2)).Compared with previously reported results, this study testifies how a simple electrode design is powerful in enhancing the functional performances of the final device.

View Article: PubMed Central - PubMed

Affiliation: Department of Information Engineering, University of Brescia - via Valotti 9, 25133 Brescia, Italy.

ABSTRACT
Layered multi-oxide concept was applied for fabrication of photoanodes for dye-sensitized solar cells based on ZnO and SnO2, capitalizing on the beneficial properties of each oxide. The effect of different combinations of ZnO@SnO2 layers was investigated, aimed at exploiting the high carrier mobility provided by the ZnO and the higher stability under UV irradiation pledged by SnO2. Bi-oxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO2 (1.20%) and ZnO (1.03%). Synergistic cooperation is effective for both open circuit voltage and photocurrent density: enhanced values were indeed recorded for the layered photoanode as compared with bare oxides (Voc enhanced from 0.39 V in case of bare SnO2 to 0.60 V and Jsc improved from 2.58 mA/cm(2) pertaining to single ZnO to 14.8 mA/cm(2)). Improved functional performances of the layered network were ascribable to the optimization of both high chemical capacitance (provided by the SnO2) and low recombination resistance (guaranteed by ZnO) and inhibition of back electron transfer from the SnO2 conduction band to the oxidized species of the electrolyte. Compared with previously reported results, this study testifies how a simple electrode design is powerful in enhancing the functional performances of the final device.

No MeSH data available.