3.4. Film performance: external quantum efficiency
The influence of Eu-based PMMA film on a photovoltaic cell is best assessed by the measurement of the external quantum efficiency (EQE) with and without the luminescent layer. Fig. 5 displays the EQE spectra obtained for the reference solar cell covered with undoped glass substrate and for the reference solar cell covered with glass substrate with the Eu-based PMMA film at different concentrations with single and double layer. Results have been grouped by the coating method applied. Measurements were taken with the Eu-based PMMA layer on the front side of the glass (Fig. 1). EQEmeasured on the UV region diminish a 3% when the reference cell is only covered with the glass, due to absorption of UV photons by the glass substrate. The highest increase in EQE in the range 280–360 nm is obtained for 10% Eu-based PMMA SC (two layers) film, reaching a value of 5.8% ± 0.01 at 280 nm. The average increase in EQE within this range is 1.6% ± 0.01. This sample displays a 3 times higher increase in EQE than 10% Eu-based PMMA (two layers) deposited by TC technique. The increase in EQE for 10% Eu-based PMMA SC (two layers) film is 1.6 times higher than EQE exhibited by filmdopedwith 20% of Eu active ions. As shown in Section 3.3, the mechanism responsible for the EQE enhancement is the energy down-conversion of Eu-based PMMA films transforming the UV light (not absorbed by the solar cell) in VIS light. These results indicate that samples with concentration over 10% wt. Eu-based PMMA diminish its efficiency due to concentration quenching processes [39,40]. EQE measurements have been carried out with a layer of air placed between the glass and the reference solar cell. There fore,many of the down-converted photons are confined in the glass due to isotropic nature of the luminescence and internal reflection losses. Consequently, the EQE can be further improved avoiding the air gap by encapsulation process in EVA.
3.4. ภาพยนตร์: ควอนตัมภายนอกอย่างมีประสิทธิภาพ The influence of Eu-based PMMA film on a photovoltaic cell is best assessed by the measurement of the external quantum efficiency (EQE) with and without the luminescent layer. Fig. 5 displays the EQE spectra obtained for the reference solar cell covered with undoped glass substrate and for the reference solar cell covered with glass substrate with the Eu-based PMMA film at different concentrations with single and double layer. Results have been grouped by the coating method applied. Measurements were taken with the Eu-based PMMA layer on the front side of the glass (Fig. 1). EQEmeasured on the UV region diminish a 3% when the reference cell is only covered with the glass, due to absorption of UV photons by the glass substrate. The highest increase in EQE in the range 280–360 nm is obtained for 10% Eu-based PMMA SC (two layers) film, reaching a value of 5.8% ± 0.01 at 280 nm. The average increase in EQE within this range is 1.6% ± 0.01. This sample displays a 3 times higher increase in EQE than 10% Eu-based PMMA (two layers) deposited by TC technique. The increase in EQE for 10% Eu-based PMMA SC (two layers) film is 1.6 times higher than EQE exhibited by filmdopedwith 20% of Eu active ions. As shown in Section 3.3, the mechanism responsible for the EQE enhancement is the energy down-conversion of Eu-based PMMA films transforming the UV light (not absorbed by the solar cell) in VIS light. These results indicate that samples with concentration over 10% wt. Eu-based PMMA diminish its efficiency due to concentration quenching processes [39,40]. EQE measurements have been carried out with a layer of air placed between the glass and the reference solar cell. There fore,many of the down-converted photons are confined in the glass due to isotropic nature of the luminescence and internal reflection losses. Consequently, the EQE can be further improved avoiding the air gap by encapsulation process in EVA.
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