Multi-Functional Spirobifluorene Phosphonate Based Exciplex Interface Enables V<sub>oc</sub> Reaching 95% of Theoretical Limit for Perovskite Solar Cells.
basic_science · Level V
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- Record sourced from PubMed, PMID 38299926.
- Also identified by DOI 10.1002/adma.202313099.
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Abstract
Metal halide perovskite solar cells (PSCs) show significant advancements in power conversion efficiency (PCE). However, the open-circuit voltage (V<sub>OC</sub>) of PSCs is limited by interfacial factors such as defect-induced recombination, energy band mismatch, and non-intimate interface contact. Here, an exciplex interface is first developed based on the strategically designed and synthesized two spirobifluorene phosphonate molecules to mitigate V<sub>OC</sub> loss in PSCs. The exciplex interface constructed by the intimate contact between the multi-functional molecules and hole transport layer takes the roles to promote the hole extraction by donor-acceptor interaction, passivate coordination-unsaturated Pb<sup>2+</sup> defects by equipped phosphonate groups, and optimize the energy level alignment. As a result, a record V<sub>OC</sub> of 1.26 V with a perovskite bandgap of 1.61 eV is achieved, representing over 95% of theoretical limit. This advancement leads to an increase in PCE from 21.29% to 24.12% and improved stability. The exciplex interface paves the way for addressing the long-standing challenge of V<sub>OC</sub> loss and promotes the wider application of PSCs.