Multi-component engineering to enable long-term operational stability of perovskite solar cells

With a record efficiency above 25%, the main hurdle for the commercialization of perovskite solar cells (PSCs) is their long-term operational stability. Although different strategies have been applied, the stability of PSCs is still far below the 25 year requirement demonstrated by commercial photovoltaic technologies. To advance in the former, a lab-scale stability analysis should resemble real testing conditions, and this is only possible through the interaction of several stress factors. Here, we briefly introduce the reader to the general degradation mechanisms observed on PSCs and the state-of-the-art strategies applied to realize long-term stable devices. Finally, we highlight the imperative need to engineer multiple components of the PSCs simultaneously and propose a rational design of PSC's constituents to obtain long-term operational solar cells. This perspective article will benefit the progression of PSCs as a reliable photovoltaic technology

Perovskite solar cells : stability lies at interfaces

Perovskite solar cells are developing fast but their lifetimes must be extended. Now, large-area printed perovskite solar modules have been shown to be stable for more than 10,000 hours under continuous illuminatio

Additive engineering for stable halide perovskite solar cells

Halide perovskite solar cells (PSCs) have already demonstrated power conversion efficiencies above 25%, which makes them one of the most attractive photovoltaic technologies. However, one of the main bottlenecks towards their commercialization is their long-term stability, which should exceed the 20-year mark. Additive engineering is an effective pathway for the enhancement of device lifetime. Additives applied as organic or inorganic compounds, improve crystal grain growth enhancing power conversion efficiency. The interaction of their functional groups with the halide perovskite (HP) absorber, as well as with the transport layers, results in defect passivation and ion immobilization improving device performance and stability. In this review, we briefly summarize the different types of additives recently applied in PSC to enhance not only efficiency but also long-term stability. We discuss the different mechanism behind additive engineering and the role of the functional groups of these additives for defect passivation. Special emphasis is given to their effect on the stability of PSCs under environmental conditions such as humidity, atmosphere, light irradiation (UV, visible) or heat, taking into account the recently reported ISOS protocols. We also discuss the relation between deep-defect passivation, non-radiative recombination and device efficiency, as well as the possible relation between shallow-defect passivation, ion immobilization and device operational stability. Finally, insights into the challenge and criteria for additive selection are provided for the further stability enhancement of PSCs

Solid state dye sensitized solar cells applying conducting organic polymers as hole conductors

Solid-state dye sensitized solar cells (SSDSCs) applying mesoporous TiO electrodes sensitized with Ru complex dye Z907 and conducting organic polymers as the hole transport material (HTM) are prepared. We employ the in-situ photo-electrochemically polymerization technique (PEP)[1-3] in order to obtain, in a single step, the conducting organic polymer on the TiO /Dye electrode. We developed a modification of reported method [2] which allows the polymer poly(3,4-ethylenedioxythiophene) (PEDOT) by different electrochemical techniques applying constant-voltage and constant-current methods. Polymer morphology and its influence on solar cell performance were studied. Overall conversion efficiency above 2% (AM 1.5, 100 mW cm) was obtained

Effect of testing conditions on the photovoltaic performance of ZnO-based dye sensitized solar cells

Dye-sensitized solar cells based on vertically-aligned ZnO nanorod, were analyzed at different conditions. Stability tests showed an improvement on solar conversion efficiency between ∼20% (1000 W/m) and ∼50% (1800 W/m). This behavior was ascribed to the physisorption/ chemisorption of the N-719 dye on the ZnO due to UV light. Studies at different temperatures proved that the performance of the cells can double when decreasing temperature from 72°C to room temperature. An increase on the efficiency and decrease in FF was observed when light intensity is increased. IPCE analyses were used to monitor the stability of the solar cells with time

Application of MEH-PPV/SnO2 bilayer as hybrid solar cell

The applications of conducting organic polymers in combination with semiconductor oxides are promising candidates as active materials for air-stable hybrid electronic applications such as transistors, light emitting diodes or organic photovoltaics. In this work, we report our last results on the application of SnO thin films in all solid-state hybrid solar cells. We also compare the results with other five solar cells developed in our laboratories applying MEH-PPV and semiconductor oxides like TiO, NbO, ZnO, CeO or CeO-TiO . In this work, SnO thin films, obtained from sol-gel solutions, have been applied in HSC in a configuration ITO/SnO /MEH-PPV/Ag. The effects of factors, such as UV light, polymer thickness, stabilization in the dark and performance under irradiation conditions, have been investigated. Open circuit voltage and short circuit current values were about -0.45 V and 0.17 mA/cm, with fill factors around 30%. Photoaction spectra show the activity of the semiconductor oxide below 340 nm and about 490 nm for the polymer. Lifetime behavior of the HSC showed an initial increase in current density reaching a maximum after about 1 h of irradiation. Blocking the UV-wavelength range by the application of a filter showed no significant difference in HSC properties with respect to the sample without UV filter. Comparison with other 5 semiconductor oxides revealed a direct relation between semiconductor oxide applied and V from the solar cell

Above-Bandgap Photovoltages in Antiferroelectrics

Altres ajuts: COST Action StableNextSol project MP1307The closed circuit photocurrent and open circuit photovoltage of antiferroelectric thin films were characterized both in their ground (antipolar) state and in their polarized state. A sharp transition happens from near zero to large photovoltages as the polarization is switched on, consistent with the activation of the bulk photovoltaic effect. The AFE layers have been grown by a solution processing method (sol?gel synthesis followed by spin coating deposition) onto fluorine-doped tin oxide (FTO), a transparent conducting oxide with low sheet resistance and a higher resilience to high-temperature processing than indium tin oxide and a standard for solar cells such as organometal trihalide perovskites. Light absorption confirmed that the PZO films are, as expected, wide-band gap semiconductors with a gap of 3.7.8 eV and thus highly absorbing in the near-ultraviolet range. On a virgin sample, there is no shortcircuit photocurrent, consistent with the antipolar nature of the ground state. As an external bias voltage is applied, the current remains negligible until suddenly, at the coercive voltage, a spike is observed, corresponding to the transient displacement current caused by the onset of polarization

Electrochemically synthesized mesoporous thin films of ZnO for highly efficient dye sensitized solar cells

Abstract In this work, nanostructured thin films of ZnO were electrochemically grown on FTO substrates. The morphology was tuned by modifying the synthesis parameters. The synthesis was carried out by applying Zn(NO3)·6H2O as the sole component of the aqueous electrolyte, avoiding the use of capping agents. The composition and morphology of the prepared ZnO were characterized by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), respectively. The as-deposited films were applied as electrodes in dye sensitized solar cells (DSCs). The performance of the cells was investigated by J×V curves and IPCE (incident photon to charge carrier efficiency) measurements. The SEM analysis demonstrated a direct relationship between ZnO morphology and Zn precursor concentration. It has been shown that the lower the concentration is, the more porous the morphology is. Increasing the amount of dye adsorbed on the ZnO decreased the power conversion efficiency of the final DSCs. The best cell presented the following parameters: open circuit voltage VOC=0.59V, short circuit current JSC=7.64mA/cm2, fill factor FF=50.41%, and power conversion efficiency PCE=2.27%

Enhancement of TiO2 nanoparticle properties and efficiency of dye-sensitized solar cells using modifiers

A low-temperature hydrothermal process developed to synthesizes titania nanoparticles with controlled size. We investigate the effects of modifier substances, urea, on surface chemistry of titania (TiO) nanopowder and its applications in dye-sensitized solar cells (DSSCs). Treating the nanoparticles with a modifier solution changes its morphology, which allows the TiO nanoparticles to exhibit properties that differ from untreated TiO nanoparticles. The obtained TiO nanoparticle electrodes characterized by XRD, SEM, TEM/HRTEM, UV-VIS Spectroscopy and FTIR. Experimental results indicate that the effect of bulk traps and the surface states within the TiO nanoparticle films using modifiers enhances the efficiency in DSSCs. Under 100-mW cm simulated sunlight, the titania nanoparticles DSSC showed solar energy conversion efficiency = 4.6 %, with V = 0.74 V, J = 9.7324 mA cm, and fill factor = 71.35

Performance and stability of mixed FAPbI3(0.85)MAPbBr3(0.15) halide perovskite solar cells under outdoor conditions and the effect of low light irradiation

We demonstrate for the first time, the real lifetime response of mixed halide perovskite solar cells (PSCs) for >1000 h under outdoor conditions and the exceptional photoresponse observed at low-light intensities attributed to the ionic-electronic nature of the material. The investigated devices were fabricated by utilizing mixed perovskites containing formamidinium (FA) and methylammonium (MA) cations, in a one step solution-process method through a solvent engineering approach. The devices' architecture is FTO/TiO (blocking layer) TiO (mesoporous)/FAPbIMAPbBr/Spiro-OMeTAD/Au. Notably, low short circuit current (J) was observed at low light intensities (1000 h under real outdoor conditions and the strong ionic component observed at low light irradiation