PHOTOELECTROCHEMICAL AND SPECTROPHOTOMETRIC STUDIES ON DYE-SENSITIZED SOLAR CELLS (DSCS) AND STABLE MODULES (DSCMS) BASED ON NATURAL APOCAROTENOIDS PIGMENTS

ABSTRACT

We present a study on dye-sensitized solar cells (DSCs) and we fabricate dye-sensitized solar modules (DSCMs) based on natural apocarotenoids extracted from the achiote's seeds (annatto). Use of less polar solvent such as diethyl ether improves the bixin concentration in the annatto extract which, was employed as sensitizer in the devices. We measure IPCE max (∼33%) and estimate ϕinj≥0.438 for annatto. By accurate and progressive optimization of both TiO2 multilayer photoanode and of electrolyte composition an efficiency (η) around 1.6%, is achieved, with an improvement of about ∼742% compare to the best performance for annatto extract, so far reported. DSCM shows stability which overcomes 1000 h (shelf-life test), under 1 sun, and produces a battery capacity of ∼46.8 Ah, the equivalent to ∼15 type AAA standard battery, in a similar time period. Although annatto based DSCMs are still below the efficiency requirements for practical applications for large scale industry, our encouraging results, testify the potentiality of this pigment in the production of non-toxic, cheap, long term stable and environmentally friendly vegetable based solar devices, as alternatives to batteries for small electronic goods market.

Giuseppe Calogero, Jessica Barichello, Ilaria Citro, Paolo Mariani, Luigi Vesce, Antonino Bartolotta, Aldo Di Carlo, Gaetano Di Marco

Dyes and Pigments 155 (2018) 75-83
doi: 10.1016/j.dyepig.2018.03.021

https://doi.org/10.1016/j.dyepig.2018.03.021

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

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

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

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 

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

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

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

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

ENHANCED CHARGE SEPARATION EFFICIENCY IN DNA TEMPLATED POLYMER 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