Efficient Naphthalene Imide-Based Interface Engineering Materials for Enhancing Perovskite Photovoltaic Performance and Stability

The ways to overcome surface charge recombination and poor interface contact are still the central challenges for the development of inorganic-organic hybrid halide perovskite solar cells (PSCs). [6,6]-Phenyl C₆₁ butyric acid methyl ester (PCBM) is commonly employed in PSCs, but it has some disadvantages including high charge recombination and poor surface coverage. Therefore, the addition of an interfacial engineering layer showing efficient surface passivation, electron extraction, and excellent interface contact can solve the above problems. Furthermore, by employing interface engineering with a spike structure of the energy levels, the reduced energy losses are beneficial to elevating the open-circuit voltage (V_oc) in PSCs. Herein, the linear naphthalene imide dimer containing an indacenodithiophene unit (IDTT2NPI) has been developed as an excellent interface engineering material to strengthen the perovskite performance. The introduction of a spike interface on the top of a methylammonium lead triiodide (MAPbI₃) film resulted in a high V_oc of 1.12 V with the optimal efficiency reaching 20.2%. The efficiency enhancement can be traced to the efficient surface passivation and enhanced interface contact. The mechanism of IDTT2NPI as the interface engineering layer was investigated by both experiments and theoretical calculations. This work provides a promising naphthalene imide-based interfacial material for high-efficiency and stable PSCs.