19.6% HTL-free carbon electrode-based perovskite record efficiency!

• Carbon-electrode-based perovskite solar cells (C-PSCs ) with hole transport layers (HTLs ) have great potential for commercial applications due to their great advantages of low cost and high stability. However, the huge energy level mismatch between perovskite and carbon electrodes severely limits the photovoltaic performance. 3D/2D perovskite heterostructures have been widely adopted to regulate the energy level arrangement, but achieving a large built-in electric field (Vbi) remains a great challenge.

  
  

  Here, Zhong Xinhua, Pan Zhenxiao and others from South China Agricultural University proposed a molecular dipole moment engineering to regulate the interface energy level and Vbi of 3D/2D perovskite heterojunction. Experimental and theoretical results show that organic cations with ultra-large dipole moments increase the work function of two-dimensional perovskites, thereby forming p-type two-dimensional perovskites. In addition, an ultra-thick (> 200 nm) 2D perovskite layer was constructed on the surface of the 3D perovskite film. This led to the construction of a 3D/2D pn junction, which significantly enhanced Vbi.

  
  

  As a result, the formed strong 3D/2D heterojunction not only effectively passivates defect states but also significantly facilitates the extraction of photogenerated holes. The device achieves a new record efficiency of 20.08% (certified as 19.6%) for HTL-free C-PSCs. The unpackaged device retains 96% of its initial value after 1000 hours of operation at the maximum power point.

• 
• 
• 
• 
• 
• 

• Y. Lin, Ultra-large dipole moment organic cation derived 3D/2D pn heterojunction for high-efficiency carbon-based perovskite solar cells. Energy Environ. Sci., 2024.

  
  

  DOI: 10.1039/D4EE00568F

  
  

  https://pubs.rsc.org/en/content/articlelanding/2024/ee/d4ee00568f