Study of inverted planar CH3NH3PbI3 perovskite solar cells fabricated under environmental conditions

Organic-inorganic inverted perovskite solar cells have been analyzed. This structure uses organic semiconductors as electron and hole selective electrodes and the perovskite as light harvesting layer. The anti-solvent deposition method is a frequently used techniques in the elaboration of conventional perovskite solar cells (FTO/TiO2/ CH3NH3PbI3/Spiro-OMetad/Au). However, the anti-solvent method is seldom used in the inverted structure. In this work, we use the anti-solvent method to fabricate the perovskite film for solar cells in the ITO/PEDOT:PSS/ CH3NH3PbI3/PC61BM/Ag configuration, systematically studying the effect of the anti-solvent dripping time and the relative humidity in cell fabrication and performance. The morphological, optical and photovoltaic analyses indicate that the right combination of these two parameters will result in a preferential crystal growth in the (1 1 0) orientation. This allows the formation of homogeneous pinhole-free films that enhance light harvesting and reduce charge-carrier leakage, hence increasing short circuit current and fill factor to obtain a photo-con- version efficiency of about ∼10%

Degradation Analysis of Triple-Cation Perovskite Solar Cells by Electrochemical Impedance Spectroscopy

In this work, the electrical properties of different triple-cation compositions with the formula Cs0.05FA1–XMAXPb(I1–XBrX)3 have been analyzed using electrochemical impedance spectroscopy. The perovskite solar cells were subjected to ambient conditions to compare their results in terms of ambient degradation. Their morphology, optical properties, and photovoltaic performance were characterized. We analyzed the causes and effects of ambient degradation mechanisms on the devices. Electrochemical processes such as ion movement, a combination of radiative recombination and nonradiative recombination, and charge transport were detected. The MA percentage decrease in the composition of triple-cation perovskites, APbX3 produces an improvement in the stability and durability of perovskite solar cells. This enhancement is due to the reduction of the amount of ion vacancies helping to reduce the degradation in the device by avoiding the accumulation of defects.Funding for open access charge: CRUE-Universitat Jaume IS.-H.T.-C. would like to thank the Spanish Ministry of Economy, Industry and Competitiveness (postdoctoral contract Juan de la Cierva Formación FJC2019-041835-I) for the financial support during this work. This work was performed under the auspices of the Universidad Autónoma de Zacatecas

Synthesis of Alloyed CdxZn1-xS Quantum Dots for Photovoltaic Applications

This article describes the synthesis of Cdx Zn1- x S quantum dots prepared using the successive ionic layer adsorption and reaction method and incorporated into a photovoltaic device. The Cdx Zn1- x S quantum dots exhibit good optical and electrical properties. The photovoltaic device has the configuration TiO2 /Cd0.75 Zn0.25 S1 /ZnS. A photoconversion efficiency of 3.6% was obtained with this device. This efficiency corresponds to a 16% relative increment compared with a reference sample with the con- figuration TiO2 /Cd1 Zn0 S1 /ZnS. The improvement is associated with an increment in the open-circuit voltage (Voc) from 0.517 to 0.725 V. The corresponding short-circuit current density (Jsc) was reduced from 12.15 to 11.66 mA cm!2. Electrochemical impedance spectroscopy analyses confirm that the behavior of the device was due to a recombination rate reduction obtained as a result of surface passivation between the TiO2 layer and the CdxZnx-1S QDs interface

Degradation Analysis of Triple-Cation Perovskite Solar Cells by Electrochemical Impedance Spectroscopy

In this work, the electrical properties of different triple-cation compositions with the formula Cs0.05FA1–XMAXPb(I1–XBrX)3 have been analyzed using electrochemical impedance spectroscopy. The perovskite solar cells were subjected to ambient conditions to compare their results in terms of ambient degradation. Their morphology, optical properties, and photovoltaic performance were characterized. We analyzed the causes and effects of ambient degradation mechanisms on the devices. Electrochemical processes such as ion movement, a combination of radiative recombination and nonradiative recombination, and charge transport were detected. The MA percentage decrease in the composition of triple-cation perovskites, APbX3 produces an improvement in the stability and durability of perovskite solar cells. This enhancement is due to the reduction of the amount of ion vacancies helping to reduce the degradation in the device by avoiding the accumulation of defects

Panchromatic Solar-to‑H₂ Conversion by a Hybrid Quantum Dots–Dye Dual Absorber Tandem Device

Solution-processed mesoscopic oxide semiconductor-based materials offer potentially low-cost and high stability alternative for next generation of water to hydrogen conversion photoelectrochemical cells (PEC). In the present study, we demonstrate the effective unassisted H₂ generation by a tandem device based on a quantum dot (QD)–dye dual absorber system. These systems are constituted by a TiO₂ mesoscopic photoanode sensitized with CdS QDs and a dye sensitized solar cell (DSSC), based on ruthenium dye, connected in series. This solar cell supplies the needed photovoltage to induce photodriven hydrogen production. Opto-electrochemical characterization of the single components allows the prediction of the operational photocurrents and a reliable estimation of the theoretical power conversion efficiencies of tandem systems. Evolved hydrogen under simulated solar illumination was collected, and solar to hydrogen conversion efficiencies (STH) were obtained. The tandem devices have demonstrated high stability in aqueous medium and solar-to-hydrogen conversion efficiency of (0.78 ± 0.04)%, near tripling the efficiency of single QD based photoanodes. These results highlight the importance of the design of hybrid photoanodes combining the effect of different light absorbers working in parallel tandem devices for the development of efficient H₂ generation QD-based photoelectrochemical cells