Efficient near-infrared harvesting in perovskite–organic tandem solar cells – Nature

Report on Efficient Near-Infrared Harvesting in Perovskite–Organic Tandem Solar Cells

Introduction

The tunability of broad bandgaps in both perovskites and organic semiconductors facilitates the development of perovskite–organic tandem solar cells with high theoretical efficiencies. Despite this potential, certified efficiencies of perovskite–organic tandem solar cells have lagged behind single-junction perovskite solar cells. This shortfall is primarily due to insufficient near-infrared photocurrent generation in narrow-bandgap organic subcells.

Research Objectives and Design

This study focuses on designing and synthesizing an asymmetric non-fullerene acceptor (NFA), named P2EH-1V, which incorporates a unilateral conjugated π-bridge. This design aims to reduce the optical bandgap to 1.27 eV while maintaining optimal exciton dissociation and nanomorphology, critical for efficient solar cell performance.

Key Findings and Technological Advancements

1. Efficient Charge Transfer: Transient absorption spectroscopy confirmed efficient hole transfer from P2EH-1V to the donor polymer PM6, enhancing charge generation.
2. Reduced Voltage Losses: Devices utilizing P2EH-1V demonstrated reduced non-radiative voltage losses of 0.20 eV without compromising charge-generation efficiency.
3. High Organic Bottom Cell Efficiency: Achieved a 17.9% efficiency with a high short-circuit current density (J_sc) of 28.60 mA cm⁻².
4. Minimized Interface Recombination: Interface recombination losses were minimized, enabling the perovskite top cell to reach an open-circuit voltage (V_oc) of 1.37 V and a fill factor (FF) of 85.5%.
5. Record Tandem Cell Efficiency: These improvements culminated in perovskite–organic tandem solar cells achieving a record efficiency of 26.7% (certified at 26.4%) over an aperture area greater than 1 cm².

Alignment with Sustainable Development Goals (SDGs)

• SDG 7 – Affordable and Clean Energy: The development of highly efficient perovskite–organic tandem solar cells contributes directly to increasing the share of renewable energy in the global energy mix by providing advanced solar technologies with enhanced energy conversion efficiencies.
• SDG 9 – Industry, Innovation, and Infrastructure: This research exemplifies innovation in material science and renewable energy technology, promoting sustainable industrialization and fostering innovation in clean energy infrastructure.
• SDG 13 – Climate Action: By improving solar cell efficiency and enabling better utilization of solar energy, this advancement supports efforts to combat climate change through reduced reliance on fossil fuels and lower greenhouse gas emissions.
• SDG 12 – Responsible Consumption and Production: The design of efficient organic semiconductors with reduced energy losses aligns with sustainable production practices by maximizing resource efficiency and minimizing waste.

Conclusion

The synthesis of the asymmetric non-fullerene acceptor P2EH-1V and its integration into perovskite–organic tandem solar cells represent significant progress toward overcoming the limitations of near-infrared photocurrent generation in organic subcells. The resulting record efficiency of 26.7% demonstrates the potential of these tandem cells to contribute meaningfully to sustainable energy solutions, supporting multiple SDGs focused on clean energy, innovation, and climate action.

1. Sustainable Development Goals (SDGs) Addressed or Connected

• SDG 7: Affordable and Clean Energy – The article focuses on the development of perovskite–organic tandem solar cells with improved efficiency, directly contributing to the goal of ensuring access to affordable, reliable, sustainable, and modern energy for all.
• SDG 9: Industry, Innovation and Infrastructure – The research involves innovation in solar cell technology, promoting sustainable industrialization and fostering innovation.
• SDG 13: Climate Action – By advancing solar energy technologies, the article supports efforts to combat climate change and its impacts through cleaner energy solutions.

2. Specific Targets Under Those SDGs Identified

• SDG 7 Targets:
  • Target 7.2: Increase substantially the share of renewable energy in the global energy mix.
  • Target 7.3: Double the global rate of improvement in energy efficiency.
• SDG 9 Targets:
  • Target 9.4: Upgrade infrastructure and retrofit industries to make them sustainable, with increased resource-use efficiency and greater adoption of clean and environmentally sound technologies.
  • Target 9.5: Enhance scientific research, upgrade the technological capabilities of industrial sectors.
• SDG 13 Targets:
  • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters.
  • Target 13.2: Integrate climate change measures into national policies, strategies, and planning.

3. Indicators Mentioned or Implied to Measure Progress

• Energy Conversion Efficiency (%) – The article reports specific efficiency percentages of the solar cells (e.g., 26.7% for tandem solar cells, 17.9% for the organic bottom cell), which serve as key indicators of technological progress and energy efficiency improvements.
• Short-Circuit Current Density (J_sc) – Measured in mA/cm², indicating the photocurrent generated, reflecting the performance of the solar cells.
• Open-Circuit Voltage (V_oc) – Voltage under open-circuit conditions, indicating voltage losses and device performance.
• Fill Factor (FF) – Represents the quality of the solar cell’s electrical output.
• Reduction in Non-Radiative Voltage Losses – Quantified in electron volts (eV), indicating improvements in device efficiency.

These indicators relate to the performance and efficiency of renewable energy technologies, which are critical for tracking progress toward SDG targets on clean energy and innovation.

4. Table of SDGs, Targets, and Indicators

Source: nature.com