Influence of compact TiO2 layer on the photovoltaic characteristics of the organometal halide perovskite-based solar cells

A series of perovskite-based solar cells were fabricated wherein a compact layer (CL) of TiO₂ of varying thickness (0–390 nm) was introduced by spray pyrolysis deposition between fluorine-doped tin oxide (FTO) electrode and TiO₂ nanoparticle layer in perovskite-based solar cells. Investigations of the CL thickness-dependent current density–voltage (J–V) characteristics, dark current, and open circuit voltage (V_oc) decays showed a similar trend for thickness dependence. A CL thickness of 90 nm afforded the perovskite-based solar cell with the maximum power conversion efficiency (η, 3.17%). Furthermore, two additional devices, perovskite-based solar cell omitting hole transporting materials layer and cell without the TiO₂ nanoparticles, were designed and fabricated to study the influence of the CL thickness on different electron transport paths in perovskite-based solar cells. Solar cells devoid of TiO₂ nanoparticles, but with perovskite and organic hole-transport materials (HTMs), exhibited sustained improvement in photovoltaic performances with increase in the thickness of CL, which is in contrast to the behavior of classical perovskite-based solar cell and common solid state solar cell which showed optimal photovoltaic performances when the thickness of CL is 90 nm. These observations suggested that TiO₂ nanoparticles play a significant role in electron transport in perovskite-based solar cells.     

Performance analysis of dye solar cell with additional TiO2 layer under different light Intensities

Deployment of dye solar cells (DSCs) for building integration application would require a highly efficient solar cell that work well in diffused light. In order to improve the efficiency of dye solar cell, an additional layer of ultrathin anatase titanium dioxide (TiO₂) has been deposited for strengthening the adhesion of the porous TiO₂-based photo electrode to the conductive transparent substrate, which can lead to an enhancement in electron transportation. Fabricated cells of 1 cm² area were tested under different light intensities (100, 33 and 10 mW cm⁻²) and characterized by scanning electron microscopy (SEM), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). Analysis showed an increment in overall quantum conversion efficiency (η), as high as 35% compared to the standard cell without the additional layer of TiO₂. EIS analysis has proven that the additional ultrathin anatase layer has improved the collection efficiency (Φ_COLL) as the result of the enhancement in both electron transport and lifetime within the porous TiO₂ film which translated into better conversion efficiency of DSCs.     

Transient photovoltage and dark current analysis on enhanced open-circuit voltage of polymer solar cells with hole blocking TiO2 nanoparticle interfacial layer

The open-circuit voltage of bulk heterojunction polymer solar cells utilizing 1,8-diiodooctane (DIO) as a processing additive was greatly improved by using an organic layer coated TiO₂ nanoparticle interfacial layer inserted between the active layer and the Al electrode. The transient photovoltage measurement revealed that there was significant non-geminate recombination at the DIO-processed active layer/Al electrode interface. Reduced open-circuit voltage (V_OC) of the photovoltaic devices and high water contact angle of the DIO-processed active layer showed that the DIO-processed active layer has an undesirable surface composition for the electron collection. The organic layer coated TiO₂ nanoparticle interfacial layer effectively prevented the non-geminate recombination at the active layer/Al interface. As a result, we were able to significantly improve the V_OC and power conversion efficiency from 0.46 V and 2.13% to 0.62 V and 3.95%, respectively.     

Efficient dye-sensitized solar cells based on CNTs and Zr-doped TiO2 nanoparticles

The light scattering, harvesting and adsorption effects in dye-sensitized solar cells (DSSCs) are studied by preparation of coated carbon nanotubes (CNTs) with TiO₂ and Zr-doped TiO₂ nanoparticles in the forms of mono- and double-layer cells. X-ray diffraction (XRD) analysis reveals that the phase composition of Zr-doped TiO₂ electrode is a mixture of anatase and rutile phases with major rutile content, whereas it is the same mixture with major anatase content for coated CNTs with TiO₂. Furthermore, the average crystallite size of Zr-doped TiO₂ electrode is slightly decreased with Zr introduction. Field emission scanning electron microscope (FE-SEM) images show that the porosity of Zr-doped TiO₂ electrodes is higher than that of undoped electrode, enhancing dye adsorption. UV–visible spectroscopy analysis reveals that the absorption onset of Zr-doped TiO₂ electrodes is slightly shifted to longer wavelength (the red-shift) in comparison with that of undoped TiO₂ electrode. Moreover, the band gap energy of TiO₂ nanoparticles is decreased by Zr introduction, enhancing light absorption. It is found that electron injection of monolayer TiO₂ electrode is improved by introduction of 0.025 mol% Zr, resulted in enhancement of its power conversion efficiency (PCE) up to 6.81% compared with 6.17% for pure TiO₂ electrode. Moreover, electron transport and light scattering are enhanced by incorporation of 0.025 wt% coated CNTs with TiO₂ in the over-layer of double layer electrode. Therefore, double layer solar cell composed of 0.025 mol% Zr-doped TiO₂ nanoparticles as the under-layer and mixtures of these nanoparticles and 0.025 wt% coated CNTs with TiO₂ as the over-layer shows the highest PCE of 8.19%.     

Efficient and stable inverted polymer solar cells using TiO2 nanoparticles and analysized by Mott-Schottky capacitance

The performance of both inverted and conventional polymer solar cells (PSCs) were examined with a low-temperature, solution-processed synthesized TiO₂ nanoparticles (TiO₂ NPs) as the electron extraction layer. The performance of inverted PSCs based on P3HT:PCBM bulk-heterojunction with a TiO₂ NPs layer was dramatically improved and the highest power conversion efficiency (PCE) of 4.56% was achieved via 24 h exposure in air, which is one of the highest PCEs for P3HT:PCBM bulk-heterojunction PSCs using TiO₂ as electron extraction layer. Meanwhile, the performance of inverted PSCs was superior to regular PSCs. Mott-Schottky capacitance analysis was carried out for both inverted and regular PSCs to obtain the built-in potential, the depletion width, as well as the doping level of the active layer, which all support the performance improvement of PSCs devices with inverted structure. In addition, inverted PSCs show excellent stability in air without encapsulation. The PCE can retain 87% of its original values after 400 h exposure in air, which is much better than that of regular PSCs. The results indicate that solution-processed TiO₂ NPs shows great potential applications in the fabrication of highly efficient and stable inverted PSCs as well as large-area, flexible printed PSCs.     

Binder-free MWCNT/TiO2 multilayer nanocomposite as an efficient thin interfacial layer for photoanode of dye sensitized solar cell

Multiwalled carbon nanotube/TiO₂ multilayer nanocomposite was successfully deposited on the fluorine-doped tin oxide (FTO) glass via layer-by-layer assembly technique to modify interfacial contact between the FTO surface and nanocrystalline TiO₂ layer as well as carbon nanotube/TiO₂ contacts in photoanode of dye sensitized solar cell. Using this approach, binder-free interfacial thin film was developed with nonagglomerated, well-dispersed MWCNTs on FTO and into TiO₂ matrix and with maximum covering of TiO₂ nanoparticles on MWCNTs. Introduction of MWCNTs/TiO₂ interfacial layer into the TiO₂ photoanode increased short circuit current density (J_sc) from 11.90 to 17.25 mA/cm² and open circuit voltage (V_oc) from 730 mV to 755 mV, whereas there was no notable change in the fill factor (FF). Consequently, power conversion efficiency (η) was enhanced from 5.32% to 7.53%, yielding a 41.5% enhancement. The results suggest that our simple strategy can integrate reduction of back electron reaction at FTO/TiO₂ interface with the effective charge transport ability of carbon nanotubes and possessing high surface area for efficient dye loading.     

Effect of CdS layers on opto-electrical properties of chemically prepared ZnS/CdS/TiO2 photoanodes

In the present work, CdS nanoparticles as a sensitizer were grown on the spin coated nanoporous TiO₂ film by repeated cycles of a Successive Ionic Layer Adsorption and Reaction (SILAR) method. ZnS layer was coated on the CdS/TiO₂ anodes to act as a protection layer on CdS. The crystallite size of CdS nanocrystals is calculated to be 3 nm from XRD spectra. The optical band gap of the film determined from transmittance spectra decreases from 3.46 to 2.15 eV with the increase in the number of CdS SILAR cycles. SEM and TEM analysis depict the enabled penetration of CdS (1 1 1) nanoparticles into the nanoporous TiO₂ (1 0 1) structure. EDX study confirms the presence of all the elements (Ti, Cd, S, Zn and O) found on the photoanode. The attachment of cubic structured CdS on anatase phase of TiO₂ in the photoanode is verified using Raman spectra. Photoluminescence (PL) study shows that the emission peak corresponding to TiO₂ has been slightly blueshifted due to the interaction of CdS nanoparticles in TiO₂ nanoporous structures. The electrical measurement shows that the dark and light illuminated resistivity of the preferred photoanode is 7.91 and 5.65 Ω cm respectively.     

Enhanced efficiency and stability of polymer solar cells with TiO2 nanoparticles buffer layer

TiO₂ sols synthesized with a facile solution-based method were used as a buffer layer between the active layer and the cathode Al in conventional structure polymer solar cells (PSCs). Using transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and atomic force microscopy (AFM), the morphological and crystallographic properties of synthesized TiO₂ nanoparticles (TiO₂ NPs) as well as the buffer layer were studied in detail. It was observed that by increasing H₂O in the process of peptization both the crystallinity and particle size of TiO₂ NPs were enhanced, while the particles in sol showed a narrower size distribution conformed by dynamic light scattering. Inserting TiO₂ NPs as a buffer layer in conventional structure PSCs, both the power conversion efficiency (PCE) and stability were improved dramatically. PSCs based on the structure of ITO/PEDOT:PSS/P3HT:PCBM/TiO₂ NPs/Al showed the short-circuit current (J_sc) of 12.83 mA/cm² and the PCE of 4.24%, which were improved by 31% and 37%, respectively comparing with the reference devices without a TiO₂ buffer layer. The stability measurement showed that PSC devices with a TiO₂ NPs buffer layer could retain 80% of the original PCEs after exposed in air for 200 h, much better than the devices without such a buffer layer. The effect can be attributed to the protection by the buffer layer against oxygen and H₂O diffusion into the active layers. The observations indicate that TiO₂ NPs synthesized by facile solution-based method have great potential applications in PSCs, especially for large-area printed PSCs.     

Cathodic multilayer transparent electrodes for ITO-free inverted organic solar cells

We demonstrate cathodic multilayer transparent electrodes based on a ZnS/Ag/TiO_x (ZAT) structure for ITO-free inverted organic solar cells. A quality solution-based TiO_x layer is adopted as an inner dielectric layer to modify the effective work function of Ag, ensuring the ZAT electrode works as a cathode. The effect of the TiO_x layer is seen on the open-circuit voltage of a solar cell incorporating this layer, increasing to 900 mV from 600 mV in the case of a cell with a bare Ag layer for a bulk-heterojunction of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C₇₀-butyric acid methyl ester (PCBM70). The results of a joint theoretical and experimental study indicate that the photocurrent of a ZAT-based solar cell can be significantly enhanced by carefully balancing the optical-spacer and cavity-resonance effects, both of which are modulated by the thickness of the WO₃ layer used as a hole-collection layer at the top anode side. ZAT-based inverted solar cells with an optimized structure exhibit a power conversion efficiency as high as 5.1%, which is comparable to that of the ITO-based equivalent.     

Synthesis and characterization of TiO2-doped Polyaniline nanocomposites by chemical oxidation method

Polyaniline (PANI)/TiO₂ nanocomposite samples with various dopant percentages of TiO₂ were synthesized at room temperature using a chemical oxidative method. The samples were characterized by ultraviolet-visible spectrometer, Fourier transform infrared (FTIR) spectrometer, X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAX and conductivity measurements. Incorporation of TiO₂ nanoparticles caused a slight red shift at 310 nm in the absorption spectra due to the interactions between the conjugated polymer chains and TiO₂ nanoparticles with π–π^? transition. FTIR confirmed the presence of TiO₂ in the molecular structure. In PANI/TiO₂ composites, two additional bands at 1623 cm^?1 and 1105 cm^?1 assigned to Ti–O and Ti–O^–C stretching modes were present. It can be concluded that Ti organic compounds are formed with an alignment structure of TiO₂ particles. XRD patterns revealed that, as the TiO₂ percentage was increased, the amorphous nature disappeared and the composites became more strongly oriented along the (1 1 0) direction, which showed the tetragonal structure of nanocrystalline TiO₂. SEM studies revealed the formation of uniform granular morphology with average grain size of 200 nm for (50%) PANI/TiO₂ nanocomposite samples.     

Effect of seed layer on the growth of rutile TiO2 nanorod arrays and their performance in dye-sensitized solar cells

In order to improve the performance of TiO₂ photoanode-based dye sensitized solar cells (DSSCs), rutile TiO₂ nanorod arrays (NRAs) were grown on SnO₂:F (FTO) conductive glass coated with TiO₂ seed layer by a hydrothermal method. The TiO₂ seed layer was obtained by spin-coating titanium tetraisopropoxide (TTIP) isopropanol solution with concentration in the range of 0~0.075 M. Then the effect of the thin TiO₂ seed layer on the crystal structure and surface morphology of TiO₂ NRAs and the photoelectric conversion properties of the corresponding DSSCs were investigated. It is found that TiO₂ NRAs are vertically oriented, about 1.7 μm long and the average diameter is about 35 nm for the samples derived from TTIP in the range of 0.005~0.05 M, which are more uniform and better separated from each other than those without TiO₂ seed layer (average diameter 35~85 nm). The photoelectric conversion efficiency of DSSCs based on TiO₂ NRAs with TiO₂ seed layer is larger than that without TiO₂ seed layer. Typically, the energy efficiency of DSSCs obtained from the seed solution of 0.025 M TTIP is 1.47%, about 1.8 times greater than that without TiO₂ seed layer. The performance improvement is attributed to the thinner, denser and better oriented NRAs grown on seeded-FTO substrate absorbing more dye and suppressing charge recombination at the FTO substrate/electrolyte interface.     

Solution-processed annealing-free ZnO nanoparticles for stable inverted organic solar cells

We report the development and application of high-quality zinc oxide nanoparticles (ZnO NPs) processed in air for stable inverted bulk heterojunction solar cells as an electron extraction layer (EEL). The ZnO NPs (average size ∼11 nm) were dispersed in chloroform and stabilized by propylamine (PA). We demonstrated that the ZnO NP dispersion with 4 vol.% of PA as stabilizer can be used in air directly and remains clear up to one month after preparation. Our inverted solar cells consisted of a blade-coated poly(N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole (PCDTBT) and [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM) (1: 4 by weight) active layer sandwiched between a ZnO electron extraction layer and a MoO₃/Ag anode. All solar cells with ZnO films fabricated in air using PA-stabilized ZnO dispersions prepared within a time window of one month exhibited power conversion efficiencies (PCE) above 4%. In contrast, if the ZnO film was prepared in air using regular un-stabilized ZnO NP dispersion, the PCE would drop to 0.2% due to poor film quality. More interestingly, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements indicated that the PA ligands were not covalently bonded to ZnO NPs and did not exist in the deposited ZnO films. The spin-cast ZnO thin films (without any thermal treatment) are insoluble in organic solvents and can be directly used as an EEL in solar cells. This feature is beneficial for fabricating organic solar cells on flexible polymer substrates. More importantly, our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for 50 days.     

High performance dye-sensitized solar cells (DSSCs) achieved via electrophoretic technique by optimizing of photoelectrode properties

This paper describes a simple method utilizing electrophoretic deposition (EPD) of commercial P25 nanoparticles (NPs) films on fluoride-doped tin oxide (FTO) substrate. In this process, voltage and the number of deposition cycles are well controlled to achieve TiO₂ film thickness of around 1.5–26 μm, without any mechanical compression processing. The experimental results indicate that the TiO₂ film thickness plays an important role as the photoelectrode in DSSCs because it adsorbs a large number of dye molecules which are responsible for electrons supply. Furthermore, it was found that effects of the bulk traps and surface states within the TiO₂ films on the recombination of the photo-injected electrons (electron–hole pairs) strongly depend on the TiO₂ electrode annealing temperature. Finally, a DSSC with a 24 μm thick TiO₂ film and annealed at 500 °C produced the highest conversion efficiency (η=6.56%, I_SC=16.4, V_OC=0.72, FF=0.55) with an incident solar energy of 100 mW/cm².     

Template free titiania photoanodes modified with carbon black or multi-wall carbon nanotubes: Thermal treatment at low and high temperature for the fabrication of quasi-solid state dye sensitized solar cells

A simple procedure was developed to prepare modified titiania (TiO₂) photoanodes for dye sensitized solar cells at low and high temperature in order to improve overall cell efficiency. Modification of TiO₂ films achieved by the incorporation of either carbon black powder (CBP) or multi-wall carbon nanotubes (MWCNTs). A small quantity of titanium alkoxide was added in a dispersion of titiania (TiO₂) powder consisting of nanoparticles at room temperature, which after alkoxide׳s hydrolysis helps to the connection between titiania (TiO₂) particles and to the formation of mechanically stable relatively thick films on conductive glass substrates. The absence of surfactant allowed us to prepare films at relatively low temperature (~100 °C), while the effect of sintering at a higher temperature (500 °C) was also studied. The structural properties of the films were examined with porosimetry method and microscopy analysis. Better electrical results were obtained for the MWCNT (0.1 wt%) modified TiO₂ films, with 3.14% and 4.68% conversion efficiencies under 1 sun illumination after treatment at 100 °C and 500 °C, respectively. The enhancement in photocurrent for MWCNT-TiO₂ films compared to pure TiO₂ films is attributed to the improved interconnectivity between TiO₂ nanoparticles, which further improved the electron transport through the film. For carbon doped CBP-TiO₂ cells, lower efficiencies were observed compared to pure TiO₂.     

Preparation and photocatalytic activity of Ag/bamboo-type TiO2 nanotube composite electrodes for methylene blue degradation

Photocatalysis phenomena in TiO₂ have been intensively investigated for its potential application in environmental remediation. The present work reports improved photocatalytic degradation of methylene blue dye in aqueous solution by using bamboo-type TiO₂ nanotubes deposited with Ag nanoparticles via electrochemical deposition. The photocatalytic processes are performed on Ag-modified TiO₂ bamboo-type nanotube arrays, Ag-modified smooth-walled nanotube arrays, and bare smooth-walled nanotube arrays. Both Ag-modified bamboo-type and smooth-walled nanotube arrays show improved photocatalytic degradation efficiencies (64.4% and 52.6%) compared to smooth-walled TiO₂ nanotubes of the same length (44.4%), due to the enhanced electron–hole seperation and more surface area provided by bamboo ridges. The photocatalytic activity and kinetic behavior of Ag-modified bamboo-type nanotube arrays are also optmized by tuning pulse deposition time of Ag nanoparticles. Bamboo-type nanotubes deposited with Ag nanoparticles via pulse deposition time of 0.5 s/1.5 s shows the highest methylene blue degradation efficiency of 78.5%, which represents 21.9% and 76.8% enhancement of efficiency compared to those of bare bamboo-type and smooth-walled nanotubes, respectively, indicating that a proper amount of Ag nanoparticles on TiO₂ can maximize the photocatalytic processes. In addition, overly long pulse deposition time will not further increase photocatalytic activity due to agglomeration of Ag paticles. For example, when the pulse deposition time is increased to 2 s/6 s, Ag-modified bamboo-type nanotube array exhibits a lower photocatalytic degradation efficiency of 62.9%.     

Preparation of highly photocatalytically active rutile titania nanorods decorated with anatase nanoparticles produced by a titanyl-oxalato complex solution

Rutile phase titania (TiO₂) nanorods and anatase nanoparticles were successfully synthesized from a titanyl-oxalato complex solution prepared using titanium (IV) sulfate and oxalic acid by a hydrothermal process. The impact of various hydrothermal conditions on the formation, morphology, phase, and grain size of the TiO₂ nanocrystals was investigated using fourier transformation infrared spectroscopy, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and nitrogen adsorption. The photocatalytic activities have been evaluated for the photo-decomposition of phenol under ultraviolet visible illumination. The results revealed that the TiO₂ rutile nanorods decorated with anatase nanoparticles (with ~22% anatase) prepared at 160 °C for 72 h exhibit a higher photocatalytic activity than those pure anatase nanoparticles. This behavior was closely related to the better charge carrier separation in the cases of rutile–anatase mixtures. In addition, the possible growth mechanism and phase development of the rutile nanorods and anatase nanoparticles were illustrated.     

Energy level alignment in PCDTBT:PC70BM solar cells: Solution processed NiOx for improved hole collection and efficiency

Solution-based NiO_x outperforms PEDOT:PSS in device performance and stability when used as a hole-collection layer in bulk-heterojunction (BHJ) solar cells formed with poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) and PC₇₀BM. The origin of the enhancement is clarified by studying the interfacial energy level alignment between PCDTBT or the 1:4 blended heterojunctions and PEDOT:PSS or NiO_x using ultraviolet and inverse photoemission spectroscopies. The 1.6 eV electronic gap of PEDOT:PSS and energy level alignment with the BHJ result in poor hole selectivity of PEDOT:PSS and allows electron recombination at the PEDOT:PSS/BHJ interface. Conversely, the large band gap (3.7 eV) of NiO_x and interfacial dipole (?0.6 eV) with the organic active layer leads to a hole-selective interface. This interfacial dipole yields enhanced electron blocking properties by increasing the barrier to electron injection. The presence of such a strong dipole is predicted to further promote hole collection from the organic layer into the oxide, resulting in increased fill factor and short circuit current. An overall decrease in recombination is manifested in an increase in open circuit voltage and power conversion efficiency of the device on NiO_x versus PEDOT:PSS interlayers.     

Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.     

The relation between TiO2 nano-pastes rheology and dye sensitized solar cell photoanode efficiency

TiO₂ nanoparticle pastes for screen printed semiconductive photoanodes of dye sensitized solar cells were prepared with different content (from 0 to 9 wt%) of ethyl cellulose and evaluated by rheology measurements. The effect of ethyl cellulose content in the paste is crucial for printed and sintered TiO₂ photoanode properties as thickness, roughness and amount of adsorbed dye, measured by profilometry, atomic force microscopy, IR and UV‐Vis spectroscopy. Moreover, the expressive correlation among paste rheology, layer properties and the final dye sensitized solar cell efficiency depending on the initial ethyl cellulose content was found, including correlations of the properties local maxima positions. The highest efficiency was achieved for the TiO₂ paste with 6.5 wt% of ethyl cellulose, where initial paste viscosity and thixotropy, printed layer thickness, roughness and amount of adsorbed dye achieved the local maxima (~40 Pa.s, 4.5 µm, 24 nm, 1.92×10⁻⁸ mol/cm², respectively) that indicates the optimal structure of the oxide photoanode layer. The results confirm the importance of controlled ethyl cellulose concentration and rheological properties of applied pastes for higher DSSC efficiency achievement.     

Reverse biased annealing: Effective post treatment tool for polymer/nano-composite solar cells

Hybrid organic solar cells using nano-porous TiO₂ infiltrated with MEH-PPV were made and characterized under standard AM 1.5 G solar illumination. Reverse biased annealing was performed on the fabricated cells as a post treatment and origin of the counter-diode was investigated by illuminating the cells through a UV-blocking filter. Treated devices deliver increased open circuit voltage and short circuit current density values, leading to significant increase in cell performances.