Furthermore, the second generation of solar cells is based on scarce elements, and this is a limiting factor in the price.8. However, due to low charge carrier mobility of organic semiconductors, the PCE of plasmonic organic solar cells is not yet high enough for commercialization.
Parameters of Solar Cell
- Short-Circuit Current Density (J sc )
- Open-Circuit Voltage (V oc )
- Output Power Density (Pd)
- Power Conversion Efficiency (PCE, η)
- Fill Factor (FF)
- Series Resistance (R S ) and Shunt Resistance (R SH )
PCE is the most commonly used parameter to compare the performance of one solar cell with another. Where Jmax is the current density and Vmax is the voltage at the maximum output power density point.
1.1.7 External Quantum Efficiency (EQE)
Organic Solar Cell (OSC)
Solar cells containing organic semiconductors have many intrinsic advantages such as light weight, flexibility and low manufacturing cost. The thesis generally focuses on a wet processing method for the fabrication of a solar cell with three different active semiconductor systems, namely poly (3-hexylthiophene-2,5-diyl) (rrP3HT), [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM).
Working Principle of OSC
An organic or plastic solar cell (OSC) is a type of solar cell that uses conductive organic semiconductors for light absorption and charge transport to produce electricity from sunlight by following the photovoltaic effect. Depending on the nature of the majority carriers, they are generally classified as p-type (donor) or n-type (acceptor) organic semiconductors.
Types of OSC
- Single Layer OSC
The mobility of the active layer material was found to be ~10-3 cm2/V·s, which is much less compared to single crystalline silicon (~103 cm2/V·s). In the case of single-layer OSC, there is only one place where the excitons can dissociate into free carriers, which is the interface between the active layer and the cathode electrode.
1.4.2 Bi-layer Heterojunction OSC
Bulk Heterojunction OSC
As a result, most photogenerated excitons can reach the interface and break efficiently. Since the better phase separation in the morphology of the mixed active layers increases the hole mobility of the conjugated polymer, which further helps to improve the absorption efficiency, various modifications were carried out, such as solvent annealing, varying the evaporation rate, etc., to optimize the morphology of the conjugated polymer. the active materials.
Optimization of BHJ OSC
- Development of New Materials
- Control of Active Layer Morphology
- Optimization of Device Architecture
- Incorporation of Plasmonic Metal Nanoparticles (NPs)
Most of the solar energy of the solar spectrum is concentrated in the visible and near-infrared (near-IR) regions. If a semiconducting polymer has a band gap of ~1.1 eV (equivalent to photons with a wavelength of less than 1100 nm), it can absorb at least 77% of the energy of the solar spectrum.
Thesis Synopsis
In particular, Ag and Au NPs with different sizes, shapes, surface modifications, and concentrations have been widely integrated into different layers of BHJ organic solar cells to achieve improved absorption. These results successfully explain the role of the double cathode buffer layers and their contribution to the improvement of the PCE and the overall device performance of the rrP3HT:PCBM-based BHJ solar cell.
Chapter 4 demonstrated the combined influence of plasmon induced metallic nanoparticles (NPs) and dual cathode buffer layers for significantly improving the PCE of
The combined influence of both the double NPs and the double cathode buffer layers was investigated with two mixed polymers, rrP3HT:PC61BM and rrP3HT:PC71BM. These results convincingly explained a very simple technique in which the collective effect of dual plasmonic metal NPs and dual cathode buffer layer to remarkably improve the PCE and overall device performance of rrP3HT:PCBM-based BHJ solar cells is demonstrated.
Cooperative plasmonic effect of Ag and Au nanoparticles on improving the performance of polymeric solar cells. Comparative study of the influence of LiF, NaF and KF on the performance of polymer bulk heterojunction solar cells.
Experiments
- Materials
- Characterization Details
- Device Fabrication
Again to find the effect of the molar mass ratio of the blend polymer at 150°C, the same procedure as point (a) was repeated and all the substrates were baked at 150°C for 30 min. Finally, to reveal again the effect of the cathodic buffer layer, five substrates coated with PEDOT:PSS with molar mass ratio 1:0.8 and Tan=150°C were prepared.
Results and Discussion
- Thin Film Characterization
- Photovoltaic Characterizations
EQE spectra of rrP3HT:PC71BM with (a) different donor-acceptor molar mass ratio at RT, (b) at different Tan with constant 1:0.8 donor-acceptor molar mass ratio (c) different donor-acceptor molar mass ratio and at constant Tan= 150°C and (d) different cathode buffer layer and at optimum conditions. Nyquist plots of rrP3HT:PC71BM with (a) different donor-acceptor molar mass ratio at RT, (b) at different Tan with constant 1:0.8 donor-acceptor molar mass ratio (c) different donor-acceptor molar mass ratio and at constant Tan= 150 °C and (d) different cathode buffer layer and at optimum conditions.
Conclusion
Also from the Nyquist plots (Figure 2.7), it was found that the BCP/Al contact devices have the highest shunt resistance compared to other device configurations and have a good correlation with their photovoltaic performance. It has been widely reported that by changing the molar mass concentration, the annealing temperature and the cathode interlayer can also significantly improve the photovoltaic performance of BHJ organic solar cells.
Small and Wide Angle X-ray Scattering Characterization of Mass Heterojunction Polymer Solar Cells with Different Fullerene Derivatives. Improved performance of polymer solar cells using inorganic, organic and doped cathode buffer layers.
Experiments
- Materials
The buffer layer includes some important modifications in BHJ such as adjusting the work function of the electrode, improving the selectivity to holes or electrons, improving the stability of the device, etc. LiF/Al helps improve short-circuit current density (Jsc), open-circuit voltage (Voc ), and overall power conversion efficiency (PCE) by directing majority carriers to their respective electrodes through voltage integrated generated by the electrode work function difference.12 However, there are still opportunities to increase the PCE by collecting photo-generated charge carriers from modulating the cathode contact with additional buffer layer.13.
3.1.2 Characterization Details
Device Fabrication
To demonstrate the effect of different additional buffer layers with LiF/Al cathode contact on photovoltaic device performance, solar cells were fabricated using the same procedure except for the selection of hole-blocking and electron-injecting layers. Finally, 100 nm thin film of LiF/Al (LiF = 1 nm and Al = 100 nm) cathode electrodes were thermally evaporated under base pressure of 10-6 mbar through a shadow mask that determines the active area of the device 6 mm² .
Results and Discussion
- Thin Film Characterization
A quenching of the absorption in both of these mixtures was observed, which can be attributed to the interaction between rrP3HT and PCBM. In addition, BCP is seen to form larger grain size compared to Alq3 and almost equal to BPhen.
3.2.2 Photovoltaic Characterizations
Conclusion
In this chapter, the significant effect of the inclusion of different dual cathode interlayers on the performance of the photovoltaic properties of the bulk heterojunction solar cell rrP3HT:PC61BM and rrP3HT:PC71BM was demonstrated. In this study, we were able to successfully demonstrate the key role of dual-cathode interlayers to improve the power convention efficiency of rrP3HT:PCBM-based organic heterojunction solar cells.
Correlation between structural and optical properties of composite polymer/fullerene films for organic solar cells. High-Performance Environmentally Processed Reverse Polymer Solar Cells by Interfacial Modification with a Fullerene Self-Assembled Monolayer.
Experiments
- Materials
- Characterization Details
- Device Fabrication
Schematic representation of the fabricated rrP3HT:PC61BM and rrP3HT:PC71BM based plasmonic BHJ organic solar cell. Inset of this graph, the schematic of the fabricated resist device (AL/PEDOT:PSS (with or without metal NPs at different concentration/Al) and UV-Vis spectra of AuNPs and AgNPs.
Results and Discussion
- Synthesis and Characterization of the Metal NPs
- Photovoltaic Characterizations
EQE spectra of (i) rrP3HT:PC61BM and (ii) rrP3HT:PC71BM BHJ solar cells with (a) bare PEDOT:PSS, (b) PEDOT:PSS + AgNPs and (c) PEDOT:PSS + AuNPs with different double cathode buffer layers . IQE spectra of (i) rrP3HT:PC61BM and (ii) rrP3HT:PC71BM BHJ solar cells with (a) bare PEDOT:PSS, (b) PEDOT:PSS + AgNPs and (c) PEDOT:PSS + AuNPs with different double cathode buffer layers .
Conclusion
In this study, we have successfully improved the PCE value of both the rrP3HT:PC61BM- and rrP3HT:PC71BM-based solar cells by the collective effect of the plasmonic metal NPs and the double cathode buffer layer. The results demonstrated here successfully explain the role of metal NP-modified PEDOT:PSS layers with different double cathode buffer layers and their contribution to the overall device performance.
Surface plasmonic effects of metal nanoparticles on the performance of bulk polymer heterojunction solar cells. Improving the efficiency of polymer solar cells by incorporating gold nanoparticles into all polymer layers.
Experiments
- Materials
- Characterization Details
- Device Fabrication
Due to the reduction mechanism, the color of the solution slowly changes from transparent to light. The metal NPs mixture solutions were then mixed with the PEDOT:PSS hole injecting layer (HIL) with a doping concentration of 20% (v/v).
Results and Discussion
- Photovoltaic Characterizations
Schematic of the mechanism related to the combined effect of hybrid metal NPs and double cathode interfacial layers on a P3HT:PCBM-based BHJ solar cell with (a) PEDOT:PSS + AuNPs: AgNPs (25:75), (b) PEDOT:PSS + AuNPs : AgNPs (50:50) and (c) PEDOT: PSS + AuNPs: AgNPs (75:25) in the presence of (i) BPhen/LiF/Al and (ii) BCP/LiF/Al, respectively. External quantum efficiency (EQE) spectrum of (i) rrP3HT:PC61BM and (ii) rrP3HT:PC71BM BHJ solar cells with different doping concentrations of AuNP:AgNP and different (a) LiF/Al, (b) BPhen/LiF/Al and (c) ) BCP/LiF/Al cathode intermediate layer.
Conclusion
It was also additionally found that the efficiency of BHJ solar cell is strongly influenced by the size of the metal NPs. The plasmonic metal nanoparticles were incorporated into the PEDOT:PSS layer to enhance photocurrent of the fabricated BHJ solar cell by increasing optical absorption and scattering in both the UV and visible wavelength range within the devices.
Understanding the Thickness-Dependent Performance of Organic Bulk Heterojunction Solar Cells: The Influence of Mobility, Lifetime, and Space Charge. Improved performance of polymer bulk heterojunction solar cells by reducing phase separation via solvent additives.
Experiments
- Synthesis of Different Shaped AuNPs
- Thin Film Morphology Study
The recorded UV-Vis spectra and TEM images of each of the NPs are shown in the figure. Schematic of hetero plasmonic junction solar cell fabricated with (b) PEDOT:PSS + AuNBs (c) PEDOT:PSS + AuNSs (d) PEDOT:PSS + AuNOs and (e) PEDOT:PSS + AuNR as HIL respectively.
Results and Discussion
- Photovoltaic Characterization
Schematic representation of the mechanism involved for rrP3HT:PC71BM BHJ solar cell with differently shaped AuNPs, namely (a) AuNBs, (b) AuNSs, (c) AuNOs and (d) AuNRs and BCP/LiF/Al as the dual cathode interface low. EQE spectra of (i) rrP3HT:PC61BM and (ii) rrP3HT:PC71BM plasmonic BHJ solar cells containing AuNPs of different shapes together with (a) BPhen/LiF/Al and (b) BCP/LiF/Al double cathode boundary layer.
Conclusion
Furthermore, the efficiency of BHJ solar cell was found to be strongly influenced by the size of the metal NPs. The plasmonic metal nanoparticles were incorporated into the PEDOT:PSS layer to enhance the photocurrent of the fabricated BHJ solar cell by increasing optical absorption and scattering in both the UV and visible wavelength range within the devices.
Development of lateral structures during the construction of a functional stack of P3HT:PCBM-based bulk heterojunction solar cells. Combined influence of plasmonic metal nanoparticles and double cathode interlayers for highly efficient bulk heterojunction solar cells based on rrP3HT:PCBM.
EPILOGUE
The power conversion efficiency (PCE) for both the blend polymer systems was observed to increase significantly in the presence of PEDOT:PSS + AuNPs and PEDOT:PSS + AgNPs with BCP/LiF/Al as the cathode contact compared to the bare PEDOT:PSS layer. It was observed that for both the blend polymer systems the PCE increases significantly in the presence of PEDOT:PSS + AuNPs:AgNPs (25:75) with BCP/LiF/Al as the cathode contact compared to others the superior surface plasmon resonance of the AuNPs :AgNPs (25:75) at the UV-visible spectrum compared to AuNPs:AgNPs (50:50) and AuNPs:AgNPs (75:25).
Publications
Journals
Patents
Publications Book Chapter
Journals (not included in the Thesis)
Proceedings (not included in the Thesis)
Vitae
