Electronic-resonance enhanced molecule for perovskite solar cells

Self-assembly monolayers (SAMs), which anchor to transparent conductive oxide (TCO) substrate and form an interfacial molecular dipole to extract carriers from perovskite layer, has promoted a stepwise improvement in efficiency of perovskite solar cells (pero-SCs).1-5 However, the limited intrinsic bonding strength due to constrained electron density on coordination sites incurs SAMs desorption and compromises charge extraction under operational stressors, posing a notable challenge to their long-term stability.6,7 To address this, we design a SAM with donor-acceptor-donor (D-A-D) resonant molecular structure, in which the electronic resonance increases the negative charge density at the acceptor anchoring group, significantly strengthening the phosphonic acid-indium tin oxide (ITO) anchoring bond and preventing the SAM desorption during operation. The device applying D-A-D resonant SAM possesses remarkable operational stability with negligible decay under maximum-power-point tracking (MPPT) at 85±5 °C for 1,080 h, maintains >93% after 1,080 h under metal halide (MH) lamp illumination (100 mW cm−2, 4.4% UV inside) at 85±5 °C and also retains >98% after 720 repetitive thermal cycles between −40 °C and 85 °C. Concurrently, the resonance induced charge delocalization facilitates efficient carrier transport, realizing a certified power conversion efficiencies (PCEs) of 27.69% on 0.063 cm2 devices and 23.63% with aperture area of 15.64 cm2. The certified efficiency of 26.64% is also realized on flexible substrates (0.063 cm2), demonstrating the universality of this approach across different types of substrates.