Impact of A-Site Cation Modification on Charge Transport Properties of Lead Halide Perovskite for Photovoltaics Applications

Perovskite solar cells (PSCs) have reached a formidable power conversion efficiency of 25.7% over the years of development. One of the strategies that has been responsible for the development of stable and highly efficient PSCs is modifications of the monovalent A-site cations (methylammonium, MA; formamidinium, FA; cesium, Cs, etc.) in lead halide perovskites. Herein, the impact of modifying the monovalent cation (MA, FAMA, CsFAMA, potassium-passivated CsFAMA, rubidium-passivated CsFAMA) in lead halide perovskite on their optoelectronic, charge transport, and photovoltaic behavior is systematically studied. Reduced trap density and improved charge carrier mobility after introduction of FA and Cs in the MAPb(I0.85Br0.15)3 system are confirmed. Further passivation of the triple-cation perovskite with K and Rb enhances the optoelectronic characteristics, charge transport, and charge extraction efficiency in halide perovskite solar cells

Solar Energy in Space Applications: Review and Technology Perspectives

Solar cells (SCs) are the most ubiquitous and reliable energy generation systems for aerospace applications. Nowadays, III-V multijunction solar cells (MJSCs) represent the standard commercial technology for powering spacecraft, thanks to their high-power conversion efficiency and certified reliability/stability while operating in orbit. Nevertheless, spacecraft companies are still using cheaper Si-based SCs to amortize the launching costs of satellites. Moreover, in recent years, new SCs technologies based on Cu(In,Ga)Se-2 (CIGS) and perovskite solar cells (PSCs) have emerged as promising candidates for aerospace power systems, because of their appealing properties such as lightweightness, flexibility, cost-effective manufacturing, and exceptional radiation resistance. In this review the current advancements and future challenges of SCs for aerospace applications are critically discussed. In particular, for each type of SC, a description of the device's architecture, a summary of its performance, and a quantitative assessment of the radiation resistance are presented. Finally, considering the high potential that 2D-materials (such as graphene, transition metal dichalcogenides, and transition metal carbides, nitrides, and carbonitrides) have in improving both performance and stability of SCs, a brief overview of some important results concerning the influence of radiation on both 2D materials-based devices and monolayer of 2D materials is also included

A crystal engineering approach for scalable perovskite solar cells and module fabrication: A full out of glove box procedure

In the present work we used some crystallization trends which could be classified as a Crystal Engineering (CE) approach, for deposition of a pure cubic-phase thin film of CH(3)NH(3)Pbl(3) (MAPbl(3)) on the surface of a mesoporous TiO2 layer. Accordingly, by using the CE approach, we fabricated high efficiency perovskite solar cells (PSCs) and perovskite solar modules (PSMs) utilizing several Hole Transport Layers (HTLs). We optimized the sequential deposition method, developing the entire realization procedure in air. The results show that the CE approach remarkably improved the device performance reaching a power conversion efficiency of 17%, 16.8% and 7% for spiro-OMeTAD, P3HT and HTL free (direct contact of the perovskite layer with the gold layer) PSCs, respectively. Furthermore, perovskite solar modules (active area of 10.1 cm (2)), which are fabricated by the CE approach, could reach an overall efficiency of 13% and 12.1% by using spiro-OMeTAD and P3HT as HTLs, respectively. The sealed modules showed promising results in terms of stability maintaining 70% of the initial efficiency after 350 hours of light soaking at the maximum power point

On the scaling of perovskite photovoltaics to modules and panels

Halide Perovskite photovoltaic technology can be scaled to large area modules and panels using printing processes and laser patterning. Here, we will present the progress made to scale up from small area solar cells to modules and panels up to a dimension of 0.5 sqm. Specific efforts have been devoted to developing a deposition process out of the glove box (GB) in conventional ambient air. We transfer out of the GB several coating technologies, including blade coating and slot-die. [1], [2] To do this without penalizing efficiency and stability, a specific formulation of perovskite absorber [2], [3] and doping strategies of transporting layer have been formulated. [4] These optimizations permitted to realized perovskite solar modules with an efficiency of > 17% on an active area of 43 cm 2 , keeping above 90% of the initial efficiency after 800 h thermal stress at 85 °C. [4] One of the critical issues scaling the cell to module size is the control of interface properties. We demonstrated that tuning of interface properties can be successfully obtained by applying two-dimensional (2D) materials, such as graphene [5], functionalized MoS2 [6], MXenes [7] as well as 2D Perovskite

On the scaling of perovskite photovoltaics to modules and panels

Halide Perovskite photovoltaic technology can be scaled to large area modules and panels using printing processes and laser patterning. Here, we will present the progress made to scale up from small area solar cells to modules and panels up to a dimension of 0.5 sqm. Specific efforts have been devoted to developing a deposition process out of the glove box (GB) in conventional ambient air. We transfer out of the GB several coating technologies, including blade coating and slot-die.[1,2] To do this without penalizing efficiency and stability, a specific formulation of perovskite absorber [2,3] and doping strategies of transporting layer have been formulated.[4] These optimizations permitted to realized perovskite solar modules with an efficiency of > 17% on an active area of 43 cm(2), keeping above 90% of the initial efficiency after 800 h thermal stress at 85 degrees C.[4] One of the critical issues scaling the cell to module size is the control of interface properties. We demonstrated that tuning of interface properties can be successfully obtained by applying twodimensional (2D) materials, such as graphene [5], functionalized MoS2 [6], MXenes[7] as well as 2D Perovskite

Solution-based heteroepitaxial growth of stable mixed cation/anion hybrid perovskite thin film under ambient condition via a scalable crystal engineering approach

The performance of perovskite solar cells is under direct control of the perovskite film quality and controlling the crystalinity and orientation of solution-processed perovskite film is a fundamental challenge. In this study, we present a scalable fabrication process for heteroepitaxial growth of mixed-cation hybrid perovskites (FA(1-x-y)MA(x)Cs(y))Pb(I1-xBrx)(3) in ambient atmospheric condition by using a Crystal Engineering (CE) approach. Smooth and mesoporous thin film of pure crystalline intermediate phase of PbX2 center dot 2DMSO is formed by deposition of supersaturated lead/cesium halides solution. Kinetically fast perovskite nucleation is achieved by rapid intercalation of formamidinium iodide (FAI) and methylammonium bromide (MABr) into the intermediate layer trough solvent assisted S(N)1 ligand exchange. Finally, heteroepitaxially perovskite growth is accomplished via Volmer-Weber crystal growth mechanism. All the layers are deposited under atmospheric condition (relative humidity (RH) 50-75%) with high reproducibility for various device and module dimensions. In particular, perovskite solar modules (Pmax similar to 550 mW) are successfully fabricated by blade coating under atmospheric condition. The CE approach remarkably improves the device performance by reaching a power conversion efficiency of 18.4% for small area (0.1 cm(2)), 16.5% on larger area (1 cm(2)) devices, and 12.7% and 11.6% for blade-coated modules with an active area of 17 and 50 cm(2), respectively. Non-encapsulated triple cation solar cells and modules show promising stability under atmospheric shelf life and light soaking conditions

Graphene-engineered automated sprayed mesoscopic structure for perovskite device scaling-up

One of the most thrilling developments in the photovoltaic field over recent years has been the use of organic-inorganic lead halide perovskite, such as CH3NH3PbI3 (MAPbI(3)), as a promising new material for low-cost and highly efficient solar cells. Despite the impressive power conversion efficiency (PCE) exceeding 22% demonstrated on lab-scale devices, large-area material deposition procedures and automatized device fabrication protocols are still challenging to achieve high-throughput serial manufacturing of modules and panels. In this work, we demonstrate that spray coating is an effective technique for the production of mesoscopic small- and large-area perovskite solar cells (PSCs). In particular, we report a sprayed graphene-doped mesoporous TiO2 (mTiO(2)) scaffold for mesoscopic PSCs. By successfully combining the spray coating technique with the insertion of graphene additive into the sprayed mTiO(2) scaffold, a uniform film deposition and a significant enhancement of the electron transport/injection at the mTiO(2)/perovskite electrode is achieved. The use of graphene flakes on the sprayed scaffold boosts the PCE of small- area cells up to 17.5% that corresponds to an increase of more than 15% compared to standard cells. For large-area (1.1 cm(2)) cells, a PCE up to 14.96% is achieved. Moreover, graphene-doped mTiO(2) layer enhances the stability of the PSCs compared to standard devices. The feasibility of PSC fabrication by spray coating deposition of the mesoporous film on large-area 21 x 24 cm(2) provides a viable and low-cost route to scale up the manufacturing of low-cost, stable and high-efficiency PSCs

Neutron irradiated perovskite films and solar cells on PET substrates

Flexible perovskite solar cells feature high power-per-weight ratio and low cost manufacturing, which make them very attractive for space and avionic applications. It is thus paramount to assess their response to the harsh space environment. Although an increasing number of studies have been investigating the effect of electron and proton radiation on perovskite solar cells, very few have dealt with neutron irradiation and even less with flexible devices. In this paper, the stability of unencapsulated flexible perovskite solar cells against fast neutron irradiation at two different fluence levels is evaluated, comparing commercially available spiro-OMeTAD and an inhouse modified P3HT as the hole transport materials. We observed degradation for both materials and at both fluences. Modified-P3HT cells experienced remarkable smaller voltage and current losses compared to spiroOMeTAD; still, their overall performance degraded similarly to spiro-OMeTAD devices at higher fluence, whilst it suffered a much higher drop than spiro-OMeTAD at lower fluence, as a consequence of a larger decrease in fill factor, ascribable to a sub-optimal perovskite/polymer interface. Spectral response and behavior at different light intensities of modified-P3HT cells suggest the polymer to be potentially more resilient than spiroOMeTAD under fast neutron irradiation, once the perovskite/polymer is improved, although further investigations are needed to gain more insights and push the development and adoption of flexible PSCs for space and avionic applications

Neutron irradiated perovskite films and solar cells on PET substrates

Flexible perovskite solar cells feature high power-per-weight ratio and low cost manufacturing, which make them very attractive for space and avionic applications. It is thus paramount to assess their response to the harsh space environment. Although an increasing number of studies have been investigating the effect of electron and proton radiation on perovskite solar cells, very few have dealt with neutron irradiation and even less with flexible devices. In this paper, the stability of unencapsulated flexible perovskite solar cells against fast neutron irradiation at two different fluence levels is evaluated, comparing commercially available spiro-OMeTAD and an inhouse modified P3HT as the hole transport materials. We observed degradation for both materials and at both fluences. Modified-P3HT cells experienced remarkable smaller voltage and current losses compared to spiroOMeTAD; still, their overall performance degraded similarly to spiro-OMeTAD devices at higher fluence, whilst it suffered a much higher drop than spiro-OMeTAD at lower fluence, as a consequence of a larger decrease in fill factor, ascribable to a sub-optimal perovskite/polymer interface. Spectral response and behavior at different light intensities of modified-P3HT cells suggest the polymer to be potentially more resilient than spiroOMeTAD under fast neutron irradiation, once the perovskite/polymer is improved, although further investigations are needed to gain more insights and push the development and adoption of flexible PSCs for space and avionic applications