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The Perovskino

Innovating Solar Cell Stability Assessment: The Perovskino Gizmo

In the realm of emerging solar photovoltaic technologies, assessing the operational stability of cells at the laboratory level presents a significant challenge. This challenge stems from the need for specialized equipment dedicated solely to this task over extended periods. Currently, to obtain representative data on the operational stability of a perovskite cell, continuous monitoring of its maximum power point is required for a time interval ranging from 500 to 1000 hours, as commonly reported (Figure 1).

Figure 1: T80 (hours) vs Publication date of stability tests on Perovskite Solar Cells. Source: 1. The Perovskite Databse Project; 2. Materials Zone; 3. An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles (2022)

The evaluation process involves the exclusive use of at least one potentiostat and a solar simulator for each device under study. While a solar simulator can illuminate multiple devices simultaneously, each typically requires a potentiostat to apply voltage and measure current at the cell terminals to determine its maximum power.

This equipment limitation has resulted in very few laboratories worldwide specializing in emerging photovoltaic research having the appropriate resources to conduct a comprehensive analysis of cell stability across a sufficient number of cells. This difficulty hampers the attainment of statistically significant results supporting improvements in stability regarding design and/or composition of active layers.

In summary, much more exhaustive research is needed in the area of operational stability of these devices. However, conducting tests on multiple cells over extended periods, coupled with the expensive necessary equipment, poses a significant challenge to progress in this field.

Unlike the assessment of simple cell efficiency with a current-voltage (JV) curve, which can be done quickly, economically, and automatedly, measuring operational stability is inherently a slow and costly process due to the required standard equipment. Additionally, it is complicated due to the specific characteristics of perovskite cells that cannot be evaluated with conventional algorithms used in traditional photovoltaics, where JV curves do not exhibit hysteresis issues.

This context helps understand why, despite advances in efficiency, the field of operational stability in perovskite solar cells has not progressed at the same level. This aspect of operational stability is crucial for the commercial development of emerging perovskite-based photovoltaics.

The EASI project adopted an innovative approach to address this issue, the development of the “Perovskino” gizmo.

The “Perovskino” is a maximum power point tracker for photovoltaic cells designed with a maximum cost reduction approach. Their function will be crucial for effectively and economically tracking the performance of perovskite photovoltaic cells over a long period.

The Low-Cost MPP Tracker “Perovskino”

“Perovskino” is a low-cost hardware (less than 5€ per unit) for long-term operational stability measurements in perovskite solar cells. Our research focuses on developing an innovative hardware solution for research purposes that allows a high number of simultaneous long-term stability measurements, eliminating the need for expensive and complex monitoring systems. Our hardware design is based on the Arduino platform, and specifically, our development is a shield that attaches to these Arduino UNO R3 Boards (Figure 2).

Due to the peculiarity of galvanostatically measuring cell efficiency, along with the pronounced hysteresis exhibited by perovskite devices, the “Perovskino” features a novel maximum power point tracking (MPPT) algorithm, the firmware of which we have deposited in the GitHub repository. Our galvanostatic MPPT algorithm ensures continuous and accurate tracking of cells with hysteresis. All work related to the development of this device and its code has been deposited as a preprint on arXiv Enhanced Power Point Tracking for High Hysteresis Perovskite Solar Cells: A Galvanostatic Approach and submitted to a peer-reviewed journal.

Stay tuned for updates on the groundbreaking innovations from the Perovskino gizmo, as we strive to revolutionize the assessment of operational stability in perovskite solar cells and drive forward the commercialization of this promising technology.

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EASI project en la bienal de Química 2022

La Real Sociedad Española de Química (RSEQ) celebró su XXXVIII Reunión Bienal en el Palacio de Congresos de Granada entre el 27 de junio y el 30 de junio de 2022. En esta edición estuvimos con el proyecto EASI donde presentamos unos resultados preliminares relacionados con la degradación del catión formamidinio.

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The EASI research project has already kicked off

PID2019-107893RB-I00: Heterounión entre perovskita híbrida y nanocristales para celda solar con absorción extendida y eficiencia mejorada

Proyecto Retos 2019 financiado por la AGENCIA ESTATAL DE INVESTIGACIÓN.

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Goals & Hypothesis

The EASI project proposes the assemble of a solar cell device containing simultaneously two types of light harvester materials forming a heterojunction.Specifically, EASI proposes to use hybrid halide perovskite and AgBiS2 nanocrystals.The goal is to extended absorption and improve performance compared to devices including solely one type of these light harvesters.

Hypothesis

It is expected that the better absorptivity coefficient of AgBiS2 nanocrystals compared to perovskite and its extended to infrared radiation absorption would lead to obtain devices with increased external quantum efficiency beyond 800 nm wavelength also taking advantage of the optimum energy band matching between both materials. Moreover, it has been described that the introduction of nanocrystals in perovskite-based solar cells increases their stability and hence lifetime.