Interface Engineering Drives n-i-p Perovskite Solar Cell Efficiency to Record 27.17%

Perovskite-Info China

Overview

Chinese researchers have reported a novel interface engineering strategy for n-i-p perovskite solar cells, leveraging a ligand-competitive bonding approach to create a continuously graded n⁺/n-doped SnO₂ electron transport layer. This innovation has enabled a certified steady-state power conversion efficiency of 27.17%, a new record for this architecture. The strategy effectively minimizes band misalignment and electron accumulation at the interface, thereby suppressing non-radiative recombination losses and maximizing device performance.

In Depth

Background

Perovskite solar cells (PSCs) continue to push the boundaries of photovoltaic efficiency, with the n-i-p configuration being a common and effective device architecture. However, a persistent challenge in n-i-p PSCs is optimizing the interface between the electron transport layer (ETL) and the perovskite active layer. Imperfect energy level alignment, charge accumulation, and high defect densities at this critical interface often lead to significant non-radiative recombination losses. These losses manifest as reduced open-circuit voltage (Voc) and fill factor (FF), ultimately limiting the overall power conversion efficiency (PCE). Overcoming these interfacial bottlenecks is crucial for realizing the full potential of high-performance PSCs.

Key Findings / Results

A research team from China, involving institutions such as Nankai University and Beijing Institute of Technology, has developed an innovative interface engineering strategy that has propelled n-i-p perovskite solar cell efficiency to a new record. Their breakthrough centers on a novel approach to the electron transport layer (ETL), specifically a continuously graded n⁺/n-doped SnO₂ layer, achieved through a ligand-competitive bonding strategy. This meticulous engineering resulted in a certified steady-state power conversion efficiency of 27.17%.

• Graded SnO₂ Electron Transport Layer: Unlike conventional uniform ETLs, the researchers implemented a graded doping profile within the SnO₂ layer. This gradient ensures a smoother transition in energy levels, facilitating more efficient electron extraction from the perovskite layer.
• Ligand-Competitive Bonding Strategy: This sophisticated chemical approach effectively passivates defects at the ETL/perovskite interface. By reducing defect states, the strategy minimizes detrimental non-radiative recombination pathways and prevents excessive electron accumulation, which are primary causes of efficiency loss.
• Record Efficiency: The 27.17% certified PCE is a testament to the effectiveness of this interface engineering. It represents one of the highest efficiencies reported for single-junction n-i-p perovskite solar cells, moving closer to the theoretical Shockley-Queisser limit for single-junction devices.

Technical Significance & Outlook

This achievement is highly significant for the advancement of perovskite photovoltaics. The precise control over interfacial properties, demonstrated by the graded doping and ligand-competitive bonding, provides a robust pathway to suppress energy losses and improve charge extraction. Such high efficiencies are particularly relevant for future tandem solar cell applications, where the perovskite cell acts as the top sub-cell. Furthermore, enhanced interface quality often correlates with improved long-term stability by reducing degradation pathways initiated at defects. While scaling this complex interface engineering to large areas for industrial production remains a challenge, this research provides critical insights into fundamental charge dynamics and defect management. It underscores China’s leadership in advanced materials science and device physics for next-generation solar technologies, positioning PSCs for broader commercial viability.