Pioneering Interface Configuration with Fermi-Level Tailoring for Tin Perovskite Photovoltaics.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Tin-based perovskite solar cells (TPSCs) offer environmental benefits and high theoretical efficiency but lag behind lead-based devices due to poor film quality and energy level misalignment.
• Conventional hole transport layers like PEDOT:PSS in inverted structures show suboptimal energy level alignment with perovskites, causing carrier issues and recombination.
• Addressing these limitations is crucial for advancing TPSC technology towards commercial viability.

Purpose of the Study:

• To design and synthesize a novel carbazole-based phosphonic acid self-assembled monolayer (SAM) with methylthio terminal groups.
• To engineer a composite hole transport layer (HTL) by integrating the novel SAM beneath PEDOT:PSS in inverted TPSCs.
• To enhance interfacial contact, improve energy level alignment, and suppress recombination losses for higher TPSC performance.

Main Methods:

• Synthesis of a carbazole-based phosphonic acid SAM with terminal methylthio groups.
• Fabrication of inverted TPSC devices incorporating the novel SAM as a sub-layer within the PEDOT:PSS HTL.
• Characterization of interfacial properties, charge carrier dynamics, and device performance, including power conversion efficiency (PCE) and operational stability.

Main Results:

• The designed methylthio-terminated carbazole-based phosphonic acid SAM effectively improved interfacial contact and energy level alignment within the HTL.
• The composite HTL structure significantly suppressed charge carrier recombination at the perovskite/HTL interface.
• The optimized TPSC device achieved a notable power conversion efficiency of 15.11% and demonstrated enhanced operational stability.

Conclusions:

• The developed carbazole-based phosphonic acid SAM with methylthio groups is a promising strategy for interfacial engineering in TPSCs.
• This approach effectively addresses energy level mismatch and recombination losses, leading to improved device performance.
• The findings offer valuable insights into Fermi-level tailoring for the development of high-performance, stable, and environmentally friendly tin-based perovskite solar cells.