PINT (PREIN) project

Full title of the project: Perovskite-inspired indoor photovoltaics for sustainable Internet-of-Things (PINT) (PREIN project)

More about the project:

The global Internet of Things (IoT) market is rapidly growing, with trillion new smart sensors being installed around the world by 2025. The most sensible choice for sustainable and energy-efficient IoT is to develop printable, light-weight, flexible, and low-cost IoT nodes, which do not contain toxic batteries, but instead are self-powered by the readily available ambient light, harvested by an indoor photovoltaic (IPV) technology. Among IPVs, perovskite-based devices have recently reached an outstanding indoor power conversion efficiency of 40.1%. Yet, beyond the attractive figures of merit, several open issues need still to be solved before commercialization. One main issue relates to the IPV materials and particularly the light absorber, i.e., perovskite. As traditional perovskites rely on toxic lead, harmful for the environment and leading to significant problem for IoT device recycling, there is a need to develop IPVs based on lead-free perovskite-inspired materials (PIMs) that can replicate the excellent optoelectronic properties of their toxic counterparts while being intrinsically stable (another major challenge for traditional of Pb-perovskites). 

In the previous PREIN 2022 project, TAU group has developed a new PIM based on pnictogens (elements of Group VA of the periodic table), CsMAFA-Sb (Adv. Energy Mater. 2023, in press), which has nearly ideal wide bandgap for indoor light harvesting. The corresponding IPVs displayed a record indoor efficiency for PIMs of 6.4%. Another class of materials explored by TAU in IPVs for the first time (Fig. 1) during the previous project is Cu2AgBiI6, CABI, (Small 2022, 18, 2203768; Sust. Energy Fuels 2023, in press). In the past months, flexible CABI-based solar cells were developed by VTT & TAU with promising results, which will be part of a publication currently under preparation. The exciting outcomes achieved in 2022 represent the starting point of the proposed research. The open questions to be addressed with the two classes of newly developed PIMs (CsMAFA-Sb and CABI) are the modest operational stability (i.e., under applied light and voltage as in solar cells) of IPVs and the poor sustainability of the PIMs processing. Only after addressing these challenging issues, PIM-based IPVs will get closer to their widespread application. 

PINT project will contribute to these ambitious aims by targeting the following objectives (Os): 

• O1: Develop a new family of lead-free PIMs, derived from CsMAFA-Sb and CABI, guided by DFT molecular modeling, with respect to the phase stability, bandgap, crystal structure, and defects. We believe that, by adjusting the elements at the different sites of the PIM structure, we can improve the intrinsic stability of the PIMs. To this aim, we will especially focus on the replacement of the halide part of the PIMs with a chalcogenide (e.g., S, Se) element, known to be robust, earth-abundant, and non-toxic. 
• O2: Establish an ad-hoc processing method (solvent, annealing conditions, etc) for the new PIM compositions that optimizes the film morphology and controls the crystallization for maximized charge transport ability. The processing is specifically applied to coated patterned films for module development to achieve desired voltages for IoT applications. 
• O3: Achieve sustainable low-cost manufacturing of flexible PIM-based IPVs. Aalto team will develop flexible substrates based on biowaste-based lignocellulosics, hence with a lower footprint than typically used ITO/FTO substrates. The proposed work will build on their recent concept of a multifunctional pectin composites that combine high UVA and UVB protection (important for increasing the lifetime of perovskite devices) and visible light transmittance (Chem. Eng. J. 2022, 439, 135738). In PINT the composite substrates will be made conductive by ultralong AgNW networks (Nanoscale Adv. 2022, 4, 4410) and the composite filler is optimized to increase the flexibility of the substrates and allow the same material used for encapsulation of the cells. Furthermore, in order to significantly reduce the fabrication costs, carbon-based electrodes will be realized instead of the common gold counter electrodes. Aalto team has recently developed new conductive inks based on carbonized biomass (manuscript in preparation). The film processing will prioritize industrially accepted solvents for each step of the device fabrication. To improve the device efficiency and stability, VTT will utilize optical flexible hard coatings with light in-coupling feature (Surface coatings for long-term efficiency, Tiina Leppäjärvi, Optitune, 30.01.2020, Session 7B: Energy, PRINSE 20, Oulu, Finland). 
• O4: Investigate the stability of IPVs in operando conditions. By unlocking the effect of operating conditions on the key figures of merit of lead-free IPVs we will create new knowledge on the fundamental processes in real working devices. O4 will also contribute to establishing a stability characterization protocol for IPVs, which is currently unavailable yet highly important for reliable characterization and stability evaluation.

The proposed research, though linked to existing projects at TAU (i.e., SOL-TECH funded by JAES and PERLA financed by Academy of Finland), does not overlap with the ongoing activities. In this project, we will for the first time: (i) explore chalcogenide-PIMs, (ii) look at PIM stability through advanced accelerated aging tests, and (iii) focus on the sustainability of the materials, solvents, and substrates constituting the IPVs. Finally, while strengthening the successful collaboration between TAU and VTT started in 2022, the project will provide a great opportunity for the 4 involved teams to launch a brand-new collaboration that will leverage their complementary expertise. 

PREIN PARTNERS: 

1. Hybrid Solar Cells (HSC), TAU; 
2. Solar Cell Technologies, VTT Technical Research Center; 
3. Multifunctional Materials Design, Aalto University; 
4. Molecular Modeling Research Group, UEF. 

Contact information: 

Accountable project leader: Prof. Jaana Vapaavuori ([email protected])

Project researcher: Maryam Mousavi, Doctoral Candidate ([email protected])

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