Alessandro Lorenzo Palma

Vertical TiO2 Nanorods as a Medium for Stable and High-Efficiency Perovskite Solar Modules

Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds.

Mesoscopic Perovskite Light-Emitting Diodes

Solution-processed hybrid bromide perovskite light-emitting-diodes (PLEDs) represent an attractive alternative technology that would allow overcoming the well-known severe efficiency drop in the green spectrum related to conventional LEDs technologies. In this work, we report on the development and characterization of PLEDs fabricated using, for the first time, a mesostructured layout. Stability of PLEDs is a critical issue; remarkably, mesostructured PLEDs devices tested in ambient conditions and without encapsulation showed a lifetime well-above what previously reported with a planar heterojunction layout. Moreover, mesostructured PLEDs measured under full operative conditions showed a remarkably narrow emission spectrum, even lower than what is typically obtained by nitride- or phosphide-based green LEDs. A dynamic analysis has shown fast rise and fall times, demonstrating the suitability of PLEDs for display applications. Combined electrical and advanced structural analyses (Raman, XPS depth profiling, and ToF-SIMS 3D analysis) have been performed to elucidate the degradation mechanism, the results of which are mainly related to the degradation of the hole-transporting material (HTM) and to the perovskite-HTM interface.

Laser-Patterning Engineering for Perovskite Solar Modules With 95% Aperture Ratio

Small area hybrid organometal halide perovskite based solar cells reached performances comparable to the multicrystalline silicon wafer cells. However, industrial applications require the scaling-up of devices to module-size. Here, we report the first fully laser-processed large area (14.5 cm2) perovskite solar module with an aperture ratio of 95% and a power conversion efficiency of 9.3%. To obtain this result, we carried out thorough analyses and optimization of three laser processing steps required to realize the serial interconnection of various cells. By analyzing the statistics of the fabricated modules, we show that the error committed over the projected interconnection dimensions is sufficiently low to permit even higher aperture ratios without additional efforts.

Efficient fully laser-patterned flexible perovskite modules and solar cells based on low-temperature solution-processed SnO 2 /mesoporous-TiO 2 electron transport layers

Efficient flexible perovskite solar cells and modules were developed using a combination of SnO2 and mesoporous-TiO2 as a fully solution-processed electron transport layer (ETL). Cells using such ETLs delivered a maximum power conversion efficiency (PCE) of 14.8%, which was 30% higher than the PCE of cells with only SnO2 as the ETL. The presence of a mesoporous TiO2 scaffold layer over SnO2 led to higher rectification ratios, lower series resistances, and higher shunt resistances. The cells were also evaluated under 200 and 400 lx artificial indoor illumination and found to deliver maximum power densities of 9.77 μW/cm2 (estimated PCE of 12.8%) and 19.2 μW/cm2 (estimated PCE of 13.3%), respectively, representing the highest values among flexible photovoltaic technologies reported so far. Furthermore, for the first time, a fully laser-patterned flexible perovskite module was fabricated using a complete three-step laser scribing procedure (P1, P2, P3) with a PCE of 8.8% over an active area of 12 cm2 under an illumination of 1 sun.

Technology Invention and Diffusion in Residential Energy Consumption. A Stochastic Frontier Approach

Traditional large appliances absorb a large share of residential electricity consumption and represent important targets of energy policy strategies aimed at achieving energy security. Despite being characterized by rather mature technologies, this group of appliances still offers large potential in terms of efficiency gains due to their pervasive diffusion. In this paper we analyse the electricity consumption of a set of four traditional ‘white goods’ in a panel of ten EU countries observed over 21 years (1990-2010), with the aim of disentangling the amount of technical efficiency from the overall energy saving. The technical efficiency trend is modelled through a set of technology components representing both the invention and adoption process by the means of specific patents weighted by production and bilateral import flows, which allows to overcome the rigid Stochastic Frontier framework in modelling the effect of technical change. Our results show that the derived energy demand and inefficiency trends are both related to changes in the amount of available technology embodied in energy efficient appliances. The effect is significant both in its domestic and international components and suggests an active role of innovation and trade policies for achieving efficiency targets which directly impact the amount of electricity consumed by households.

The “Double Expansion of Morbidity” Hypothesis: Evidence from Italy

The last few decades have been characterized by an increase in the number of years lived in bad health, lending support to the “Expansion of Morbidity” hypothesis. In this paper we propose the “Double Expansion of Morbidity” (DEM) hypothesis, arguing that not only life expectancy gains have been transformed into years lived in “bad health”, but also, due to an earlier onset of chronic diseases, the number of years spent in “good health” is actually reduced. Limited to the Italian case, we present and discuss a set of empirical evidence confirming the DEM hypothesis. In particular, we find that from 2004 to 2014 the average number of years spent with chronic conditions in Italy increased by 7.2 years 2.3 years of which are due to an increase in life expectancy and 4.9 years due to a reduction in the age of onset of chronic conditions. Compared with 2004, in 2014, this phenomenon generated extra public health expenditure of nearly 6.3 billion euros. We discuss the policy implications of these findings.