Halogen Bond Involved Post‐Treatment for Improved Performance of Printable Hole‐Conductor‐Free Mesoscopic Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) are considered to be the most promising next‐generation photovoltaic technology. Among all the configurations of PSCs, the printable hole‐conductor‐free mesoscopic PSC (p‐MPSC) has unique advantages on low cost, large‐area fabrication and fabulous stability, which endows it with the greatest potential for industrialization. The interfacial recombination losses, especially at the perovskite/carbon interface, are the bottleneck for further improving the power conversion efficiency (PCE) of p‐MPSCs. 2‐Bromo‐6‐fluoronaphthalene is introduced as an interfacial modulator for p‐MPSCs through post‐treatment. The bromo‐terminal acts as an electrophilic site to interact with the iodine ion in perovskite via the noncovalent halogen bond. Meanwhile, the fused ring of naphthalene is capable to accommodate electron density that is attracted from the perovskite. This interaction induces a more favorable band structure at the interface. The hole extraction is promoted and the interfacial nonradiative recombination is inhibited. Accordingly, a champion p‐MPSC with an improved PCE of 16.77% from 15.50% of the pristine device is obtained.

Halogen Bonding in Perovskite Solar Cells: A New Tool for Improving Solar Energy Conversion

“…A similar crosslinking mechanism has also been proposed for 2‐bromo‐6‐fluoronaphthalene introduced as an interfacial modulator for printable hole‐conductor‐free mesoscopic PSCs through post‐treatment. [46] …”

Carbon Electrode Endows High‐Efficiency Perovskite Photovoltaics Affordable, Fully Printable, and Durable

“…Through the rational design of perovskite compositions and perovskite-additive interaction, the PCEs based on TiO 2 /ZrO 2 /C mesoporous PSCs improved from 12.84% to 17.68%. [28][29][30][31][32] Unfortunately, one needs to carefully control the infiltration process of perovskite ink, in which the crystallization of perovskite crystals and the contact between perovskites and other active layers should be carefully optimized.…”

Ways to Improve the Performance of Triple‐Mesoscopic Hole‐Conductor‐Free Perovskite‐Based Solar Cells

“…As TOPO passivates the perovskite surface by interacting with the Pb, the 2‐bromo‐6‐fluoronaphtalene (BFN) treated the iodine ions defects. Deyi Zhang et al [ 72 ] incorporated BFN molecules as posttreatment to MCPSCs. In addition to the passivation effect of this molecule, the BFN change the energy level alignment by shifting the E f closer to the carbon's CB.…”