Stark Effect in Perovskite/TiO2Solar Cells: Evidence of Local Interfacial Order

n/

Stark Effect in Perovskite/TiO2 Solar Cells: Evidence of Local

To unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based meso-structured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films

Stark effect in perovskite/TiO2 solar cells: Evidence of local interfacial order

To unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based mesostructured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films. © 2014 American Chemical Society

Light energy harvesting with nano-dipoles

We propose a new approach for converting light energy into electrical energy, based on the photogeneration of nano-dipoles at donor-acceptor interfaces. The nano-dipoles are oriented in space so as to contribute to a collective polarization that induces a potential difference across the material, sandwiched between electrodes. A current is detected in the external circuit upon illumination. Such a device would exploit many advantages of organic semiconductors and get rid of the main limitation, namely transport. We provide a proof of concept and we discuss the ideal limit of the device based on numerical simulations. This provides design guidelines to the achievement of best performances. Simulations show that the proposed device can be an appealing opportunity with giant conversion efficiency provided some technological issues are overcome

Stark Effect in Perovskite/TiO2 Solar Cells: Evidence of Local

To unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based meso-structured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films

Growing perovskite into polymers for easy-processable optoelectronic devices

Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processability of polymers, providing a tool to control film quality and material crystallinity. We verify that the employed semiconducting polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), controls the self-assembly of CH₃NH₃PbI₃ (MAPbI₃) crystalline domains and favors the deposition of a very smooth and homogenous layer in one straightforward step. This idea offers a new paradigm for the implementation of polymer/perovskite nanocomposites towards versatile optoelectronic devices combined with the feasibility of mass production. As a proof-of-concept we propose the application of such nanocomposite in polymer solar cell architecture, demonstrating a power conversion efficiency up to 3%, to date the highest reported for MEH-PPV. On-purpose designed polymers are expected to suit the nanocomposite properties for the integration in diverse optoelectronic devices via facile processing condition

Stark Effect in Perovskite/TiO₂ Solar Cells: Evidence of Local Interfacial Order

To unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based mesostructured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films

Effect of Mesostructured Layer upon Crystalline Properties and Device Performance on Perovskite Solar Cells

One of the most fascinating characteristics of perovskite solar cells (PSCs) is the retrieved obtainment of outstanding photovoltaic (PV) performances withstanding important device configuration variations. Here we have analyzed CH3NH3PbI3–xClx in planar or in mesostructured (MS) configurations, employing both titania and alumina scaffolds, fully infiltrated with perovskite material or presenting an overstanding layer. The use of the MS scaffold induces to the perovskite different structural properties, in terms of grain size, preferential orientation, and unit cell volume, in comparison to the ones of the material grown with no constraints, as we have found out by X-ray diffraction analyses. We have studied the effect of the PSC configuration on photoinduced absorption and time-resolved photoluminescence, complementary techniques that allow studying charge photogeneration and recombination. We have estimated electron diffusion length in the considered configurations observing a decrease when the material is confined in the MS scaffold with respect to a planar architecture. However, the presence of perovskite overlayer allows an overall recovering of long diffusion lengths explaining the record PV performances obtained with a device configuration bearing both the mesostructure and a perovskite overlayer. Our results suggest that performance in devices with perovskite overlayer is mainly ruled by the overlayer, whereas the mesoporous layer influences the contact propertiesThis work was supported by the Universitat Jaume I (Project 12I361.01/1), by Spanish MINECO (MAT2013-47192-C3-1-R), by EFOR (Iniziativa CNR per il Mezzogiorno L. 191/2009 art. 2 comma 44), by PON-MAAT (Project Number: PON02_00563_3316357-CUP B31C12001230005), by PON-FORM@BEYOND-NANO, and by Regione PUGLIA (APQ Reti di Laboratorio, Project “PHOEBUS” cod. 31). The authors gratefully acknowledge Dr. Paolo Perazzelli for fruitful discussio