CHOSERESEARCHPUBLICATIONS

LOW TEMPERATURE, SOLUTION-PROCESSED PEROVSKITE SOLAR CELLS AND MODULES WITH AN APERTURE AREA EFFICIENCY OF 11%

 

low temperature perovskite s cells

 

ABSTRACT

Planar perovskite solar cells and modules were realized by using low temperature solution-process fabrication procedures. The photovoltaic performance was improved by optimizing a SnO2 electron transport layer and its interface with the perovskite layer. We achieved a power conversion efficiency (PCE) of 17.3% on small area cell (0.09 cm2) with negligible hysteresis and a steady-state PCE equal to 17.4%. Furthermore, shelf life tests showed a relative decrease of only 5% in PCE from its initial value after 1000 h of storage in dark conditions in air (RH 20%). Up-scaling of the technology was implemented entirely in air with fabrication of modules with a high aperture ratio of 91%. The modules delivered a maximum PCE of 13.1% obtained on an active area of 13.8 cm2and of 11.9% on an aperture area of 15.2 cm2 representing state of art performance for fully low temperature solution processed planar perovskite solar modules.

Emanuele Calabrò, Fabio Matteocci, Alessandro Lorenzo Palma, Luigi Vesce, Babak Taheri, L. Carlini, Igor Pis, Silvia Nappini, Janardan Dagar, Chiara Battocchio, Thomas M. Brown

DOI: 10.1016/j.solmat.2018.05.001

https://www.sciencedirect.com/science/article/pii/S0927024818302150

 

AGING EFFECTS IN INTERFACE-ENGINEERED PEROVSKITE SOLAR CELLS WITH 2D NANOMATERIALS: A DEPTH PROFILE ANALYSIS

 

aging effects interface engineered perovskite1

 

ABSTRACT

The stability of perovskite solar cells (PSCs) is a major factor limiting the market breakthrough of this technology. To understand the aging effects in PSCs is mandatory to rationally design implemented architectures and materials combining a viable deposition process, efficiency and stability. Despite of this evidence, only few experimental works succeeded in the direct quantitative characterization of aging effects in PSCs. In this work, we apply state-of-the-art X-ray photoelectron spectroscopy (XPS) depth profile analysis and time-of-flight secondary ion mass spectrometry (ToF-SIMS) 3D imaging to investigate the light-induced degradation of layers and interfaces in reference (Au/Spiro-OMeTAD/CH3NH3PbI3/m-TiO2/cTiO2/FTO) and interface-engineered mesoscopic PSCs in which graphene flakes are added into the mesoscopic TiO2 layer and a solution-processed 2H-MoS2 flakes buffer layer is added at the Spiro-OMeTAD/CH3NH3PbI3interface. Results show that the graphene addition into the mesoscopic TiO2 layer improves the stability of the PSC by reducing the locally-inhomogeneous light-induced back-conversion of the CH3NH3PbI3 layer into PbIx and PbOx species and the consequent release of iodine species, which diffuse across the interfaces and causes the modifications at the gold electrode (Au-I bonding) and the mesoscopic TiO2 (Ti-I bonding) interfaces. Moreover, where the CH3NH3PbI3 layer is preserved the gold diffusion across the entire device structure is strongly reduced even after the aging. The 2H-MoS2 flakes buffer layer allows limiting the localized diffusion of gold and the iodine diffusion in as-prepared PSCs while it is rather ineffective in preventing light-induced aging effects. Overall, thanks to the lower average degradation of the layers and interfaces, interface engineered PSCs could retain ∼60% of their initial PCE after the aging respect to less than ∼25% in the reference cells.

Yan Busby, Antonio Agresti, Sara Pescetelli, Aldo Di Carlo, Celine Noel, Jean-Jacques Pireaux, Laurent Houssiau

DOI: 10.1016/j.mtener.2018.04.005

https://www.sciencedirect.com/science/article/pii/S2468606918300303

 

ENHANCED CHARGE SEPARATION EFFICIENCY IN DNA TEMPLATED POLYMER SOLAR CELLS

 

insertion DNA nanolayer into polymer based solar cells

ABSTRACT

The insertion of a DNA nanolayer into polymer based solar cells, between the electron transport layer (ETL) and the active material, is proposed to improve the charge separation efficiency. Complete bulk heterojunction donor–acceptor solar cells of the layered type glass/electrode (indium tin oxide)/ETL/P3HT:PC70BM/hole transport layer/electrode (Ag) are investigated using femtosecond transient absorption spectroscopy both in the NIR and the UV–vis regions of the spectrum. The transient spectral changes indicate that when the DNA is deposited on the ZnO nanoparticles (ZnO‐NPs) it can imprint a different long range order on the poly(3‐hexylthiophene) (P3HT) polymer with respect to the non‐ZnO‐NPs/DNA containing cells. This leads to a larger delocalization of the initially formed exciton and its faster quenching which is attributed to more efficient exciton dissociation. Finally, the temporal response of the NIR absorption shows that the DNA promotes more efficient production of charge transfer states and free polarons in the P3HT cation indicating that the increased exciton dissociation correlates with increased charge separation.

Francesco Toschi, Daniele Catone, Patrick O'Keeffe, Alessandra Paladini, Stefano Turchini, Janardan Dagar, Thomas M. Brown

DOI: 10.1002/adfm.201707126

https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201707126

 

FACILE SYNTHESIS OF A SNO2@RGO NANOHYBRID AND OPTIMIZATION OF ITS METHANE-SENSING PARAMETERS

 

stannic oxide nanoparticles1

 

ABSTRACT

Stannic oxide nanoparticles and various compositions of SnO2@rGO (reduced graphene oxide) nanohybrids were synthesized by a facile hydrothermal method and utilized as chemiresistive methane gas sensors. To characterize the synthesized nanohybrids, BET (Brunauer-Emmett-Teller), XRD, FESEM, TEM, FTIR, and Raman techniques were used. Sensing elements were tested using a U-tube flow chamber with temperature control. To obtain the best sensor performance, i.e., the highest signal and the fastest response and recovery times, the sensing element composition, operating temperature, and gas flow rate were optimized. The highest response (change in resistance) of 47.6% for 1000 ± 5 ppm methane was obtained with the SnO2@rGO1% nanohybrid at 150 °C and a flow rate of 160 sccm; the response and recovery times were 61 s and 5 min, respectively. A sensing mechanism was suggested, based on the experiments.

Shiva Navazani, Ali Shokuhfar, Mostafa Hassanisadi, Mojtaba Askarieh, Aldo Di Carlo, Antonio Agresti

DOI: 10.1016/j.talanta.2018.01.015

https://www.sciencedirect.com/science/article/pii/S0039914018300213

 

HIGHLY EFFICIENT PEROVSKITE SOLAR CELLS FOR LIGHT HARVESTING UNDER INDOOR ILLUMINATION VIA SOLUTION PROCESSED SNO2/MGO COMPOSITE ELECTRON TRANSPORT LAYERS

 

perovskite solar cell

ABSTRACT

We present new architectures in CH3NH3PbI3 based planar perovskite solar cells incorporating solution processed SnO2/MgO composite electron transport layers that show the highest power outputs ever reported under typical 200–400 lx indoor illumination conditions. When measured under white OSRAM LED lamp (200, 400 lx), the maximum power density values were 20.2 µW/cm2 (estimated PCE = 25.0%) at 200 lx and 41.6 µW/cm2 (PCE = 26.9%) at 400 lx which correspond to a ∼ 20% increment compared to solar cells with a SnO2 layer only. The thin MgO overlayer leads to more uniform films, reduces interfacial carrier recombination, and leads to better stability. All layers of the cells, except for the two electrodes, are solution processed at low temperatures, thus low cost processing. Furthermore, ambient indoor conditions represent a milder environment compared to stringent outdoor conditions for a technology that is still looking for a commercial outlet also due to stability concerns. The unparalleled performance here demonstrated, paves the way for perovskite solar cells to contribute strongly to the powering of the indoor electronics of the future (e.g. smart autonomous indoor wireless sensor networks, internet of things etc).

Janardan Dagar, Sergio Castro-Hermosa, Giulia Lucarelli, Franco Cacialli, Thomas M. Brown

DOI: 10.1016/j.nanoen.2018.04.027

https://www.sciencedirect.com/science/article/pii/S221128551830257X

 

ON THE IMPORTANCE OF FERROELECTRIC DOMAINS FOR THE PERFORMANCE OF PEROVSKITE SOLAR CELLS

 

ferroelectric polarization patterns in MAPbI3

 

The effect of ferroelectric polarization patterns in MAPbI3 on JV characteristics has been analyzed. We discuss models for the polarization orientation pattern and magnitude of the ferroelectric domains. Simulations performed on real patterns show that the presence of ordered ferroelectric domains, even with a weak characteristic polarization magnitude enhances the power conversion efficiencies and are mandatory to reproduce the experimental J-V characteristics.

ABSTRACT

This work analyzes in detail the effect of ferroelectric polarization patterns in methylammonium lead iodide (MAPbI3) thin-films on the J-V characteristics of the corresponding solar cells. The simulations are based on a finite-element discretization of the drift-diffusion equations and take into account the polarization pattern experimentally derived from piezoresponse force micrographs. Based on the knowledge of the crystalline structure, symmetry considerations and electrical simulations, we discuss models for the polarization orientation pattern and magnitude of the ferroelectric domains. We conclude that the in-plane polarization vectors have 45° orientation towards the domain walls and form herring-bone structures. The presence of ordered ferroelectric domains, even with a weak characteristic polarization magnitude enhances the power conversion efficiencies and are mandatory to reproduce the experimental J-V characteristics.

Daniele Rossi, Alessandro Pecchia, Matthias Auf der Maur, Tobias Leonhard, Holger Röhm, Michael J. Hoffmann, Alexander Colsmann, Aldo Di Carlo

DOI: 10.1016/j.nanoen.2018.02.049

https://www.sciencedirect.com/science/article/pii/S2211285518301174

 

 

FULLY-SPRAYED FLEXIBLE POLYMER SOLAR CELLS WITH A CELLULOSE-GRAPHENE ELECTRODE

 

solar cells fully sprayed

Light, flexible and low-cost organic solar cells made entirely by spray and with an innovative cellulose and graphene-based electrode!
The work, in collaboration with the Smart Materials group of the ISTITUTO ITALIANO DI TECNOLOGIA has been published on the important magazine "Materials Today Energy".

ABSTRACT

Organic photovoltaic (OPV) technology provides energy where conventional photovoltaics are difficult to implement. The rise of efficiency due to the introduction of new polymers and the definition of strategies for the scale-up push OPV devices towards large-scale manufacturing. Here, spray coating has been employed as an easy and versatile scalable technique to deposit all the layers of flexible polymer solar cells starting from PET/ITO/Ag/ITO substrates. A foldable nanocomposite based on cellulose and sprayed graphene nanoplatelets has been applied as top electrode through lamination. The overall fabrication process has been conducted in air by using commercial materials. A significant power conversion efficiency higher than 3% has been achieved and the high quality of the lamination process has been demonstrated by bending and adhesion tests. Such photovoltaic devices are the first fully-sprayed prototypes on plastic substrate and the novel structure has also been effective for devices with active area up to 0.75 cm2.

Luca La Notte, Pietro Cataldi, Luca Ceseracciu, Ilker S. Bayer, Athanassia Athanassiou, Sergio Marras, Enrica Villari, Francesca Brunetti, Andrea Reale

Materials Today Energy

January 2018

https://doi.org/10.1016/j.mtener.2017.12.010

 

 
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