Conventional photovoltaic power supply batteries (PVBs) suffer from low integration and difficulty in miniaturization. Perovskite materials, however, can simultaneously serve as both the light-absorbing layer and cathode in solar cells, offering potential to overcome these limitations. This study proposes a dual-function material sharing strategy using ethyl violete diiodide (EVI₂), enabling modified perovskite solar cells (PSCs) to achieve a power conversion efficiency (PCE) of 26.11% (retaining 96.2% after 1000 hours). Millennial Perovskite Maximum Power Point Tracking (MPPT) utilizes AAA-grade LED solar simulators as aging light sources, enabling multi-faceted temperature control and environmental atmosphere regulation for long-term stability testing.

Furthermore, its derivative EVSnI₆ cathode cell achieves a capacity of 296.1 mAh g⁻¹ at 0.5 A g⁻¹ current density (retaining 89% capacity after 10,000 cycles at 5 A g⁻¹). The resulting all-perovskite integrated PVB system demonstrates a total efficiency of 18.54% (17.62% for the flexible version with stable photochemical charge-discharge cycles). It can also provide stable power for 24 hours to a wearable glucose monitor in smart control mode, fully demonstrating its application value in next-generation portable electronic devices.

Interaction Mechanism Between EVI₂ and Perovskite

Interaction Between EVI₂ and Perovskite

Research indicates that EVI₂ exerts its effects by forming a modification layer on the perovskite surface rather than altering its bulk structure. XPS and DFT calculations indicate that the violet-purple group of EVI₂ interacts electronically with perovskite, increasing the electron density of Pb atoms on the perovskite surface and inducing changes in its band structure (e.g., CBM shift). This facilitates interfacial charge extraction. KPFM measurements confirm that EVI₂ modification leads to a more uniform potential distribution on the perovskite surface. This optimized electronic structure significantly suppresses non-radiative recombination (extending PL lifetime from 223.5 ns to 457.4 ns) and reduces defect density (lowering trap filling limit voltage from 0.56 V to 0.31 V), laying the foundation for high-performance PSCs.

Perovskite Photovoltaic Performance

Photovoltaic Performance of Perovskite Solar Cells (PSCs)

Based on the aforementioned modification strategies, p-i-n structured perovskite solar cells were constructed (with C₆₀ as the electron transport layer and p-type organic small molecules as the hole transport layer). Key performance metrics are as follows:

The optimal cell achieved a power conversion efficiency (PCE) of 26.11%, with specific parameters: short-circuit current density of 26.17 mA cm⁻², open-circuit voltage of 1.186 V, and fill factor of 84.12%. The cell exhibited minimal hysteresis, with a forward scan PCE of 25.82% and a certified maximum power point tracking (MPPT) efficiency of 25.43%.

Outstanding stability performance: Under ISOS-L-1 protocol testing (continuous 1 sun illumination), it retained 96.2% of initial efficiency after 1000 hours, whereas unmodified cells retained only 83.2% after 800 hours; Under the more stringent ISOS-L-3 protocol, efficiency retention after 1000 hours was 93.7%, compared to only 76.2% for unmodified cells; In light-switching cycle testing (12 hours of illumination / 12 hours of darkness, totaling 30 cycles and 720 hours), the EVI₂-modified cell exhibited only a 2% efficiency loss, whereas the unmodified cell degraded by 11%.

Electrochemical Performance of ESVnI₆ Cathodes

Electrochemical Performance of Rechargeable Batteries

In battery research, the introduction of Sn²⁺ into EVI₂ led to the synthesis of an EVI₂I₆ perovskite cathode material featuring a one-dimensional organic-inorganic hybrid structure. This material exhibits outstanding air stability and oxidation resistance (as Sn²⁺ is difficult to oxidize). Theoretical calculations indicate its surface possesses strong adsorption energy for iodine species such as I₂, I₃⁻, and I₅⁻, effectively suppressing the polyiodide shuttle effect. Electrochemical testing reveals that the EVsn₂I₆ cathode enables multi-electron reversible redox reactions based on EV⁰/EV⁺/EV²⁺ and I⁻/I⁰/I⁺, exhibiting low polarization and a high average voltage (2.98 V). It exhibits outstanding rate performance (296.1 mAh g⁻¹ at 0.5 A g⁻¹, maintaining 212.4 mAh g⁻¹ at 5 A g⁻¹), retaining 89% capacity after 10,000 cycles at 5 A g⁻¹ with a capacity decay rate of only 0.0011% per cycle.

Photovoltaic-powered battery performance

Performance of All-Perovskite Photovoltaic Power Battery (PVB)

To achieve integrated conversion and storage of “solar energy - electrical energy - chemical energy,” a perovskite micro-module (efficiency 23.60%, VOC=4.41 V) composed of four series-connected sub-cells was integrated with an EVSn₂I₆ battery to construct an all-perovskite PVB. In this configuration, the PSC's silver electrode connects to the battery anode, while the ITO electrode connects to the cathode, with PET film isolating the electrolyte. This rigid PVB underwent 100 cycles of photovoltaic charging followed by constant-current discharging under 1 sun illumination, achieving an overall energy conversion efficiency of 18.54% with exceptional stability. The flexible PVB cell (based on a PEN substrate) also achieved an overall energy conversion efficiency of 17.62%, maintaining excellent mechanical durability and performance after 1000 bending cycles (8 mm radius). The cells functioned reliably at temperatures ranging from -20°C to 40°C. Integrated with an intelligent charging protection board, the flexible PVB successfully provided 24-hour uninterrupted power to a commercial continuous glucose monitor, demonstrating stable operation under sunlight, indoor lighting, and darkness.

The core innovation of this research lies in the “dual-function material sharing” strategy: EVI₂ simultaneously optimizes charge transport efficiency in perovskite solar cells and cathode stability in rechargeable batteries, ultimately overcoming the traditional bottlenecks of photovoltaic power supply cells—integration difficulties and poor stability. Performance metrics demonstrate leading-edge capabilities: the perovskite solar cell achieved 26.11% PCE with 96.2% stability over 1000 hours, the EVI SnI₆ battery maintained stability through 10,000 cycles, and the integrated PVB system delivered 18.54% overall energy conversion efficiency. The practical application of flexible batteries (powering a glucose monitor) offers a viable solution for “cordless power supply” in portable and wearable electronic devices.

Millennial Perovskite Maximum Power Point Tracking Test MPPT

The Perovskite Maximum Power Point Tracking Test MPPT utilizes A+AA+ grade LED solar simulators as aging light sources. With its advanced technology and multifunctional design, it provides robust support for perovskite solar cell research.

▶ Light Source Rating: A+AA+, Spectral Matching Grade A+, Uniformity Grade A, Long-Term Stability Grade A+

▶ Effective Spot Size: ≥250*250mm (customizable)

▶ Adjustable Irradiance: 0.2-1.5 sun, adjustable in 0.1 sun increments

▶ Independently Controllable Power Bands: 300-400 nm / 400-750 nm / 750-1200 nm

Millennial Perovskite Maximum Power Point Tracking (MPPT) Testing is not only a performance verification tool but also provides robust support for perovskite solar cell (PSC) research.