Improved Ambient-Stable Perovskite Solar Cells Enabled by a Hybrid Polymeric Electron-Transporting Layer

Naphthalene diimides: perspectives and promise

In this review, we describe the developments in the field of naphthalene diimides (NDIs) from 2016 to the presentday. NDIs are shown to be an increasingly interesting class of molecules due to their electronic properties, large electron deficient aromatic cores and tendency to self-assemble into functional structures. Almost all NDIs possess high electron affinity, good charge carrier mobility, and excellent thermal and oxidative stability, making them promising candidates for applications in organic electronics, photovoltaic devices, and flexible displays. NDIs have also been extensively studied due to their potential real-world uses across a wide variety of applications including supramolecular chemistry, sensing, host-guest complexes for molecular switching devices, such as catenanes and rotaxanes, ion-channels, catalysis, and medicine and as non-fullerene accepters in solar cells. In recent years, NDI research with respect to supramolecular assemblies and mechanoluminescent properties has also gained considerable traction. Thus, this review will assist a wide range of readers and researchers including chemists, physicists, biologists, medicinal chemists and materials scientists in understanding the scope for development and applicability of NDI dyes in their respective fields through a discussion of the main properties of NDI derivatives and of the status of emerging applications.

Efficient Inverted Perovskite Solar Cells by Employing N-Type (D-A1 -D-A2 ) Polymers as Electron Transporting Layer

It is highly desirable to employ n-type polymers as electron transporting layers (ETLs) in inverted perovskite solar cells (PSCs) due to their good electron mobility, high hydrophobicity, and simplicity of film forming. In this research, the capability of three n-type donor-acceptor₁ -donor-acceptor₂ (D-A₁ -D-A₂ ) conjugated polymers (pBTT, pBTTz, and pSNT) is first explored as ETLs because these polymers possess electron mobilities as high as 0.92, 0.46, and 4.87 cm² (Vs)^-1 in n-channel organic transistors, respectively. The main structural difference among pBTT, pBTTz, and pSNT is the position of sp² -nitrogen atoms (sp² -N) in the polymer main chains. Therefore, the effect of different substitution positions on the PSC performances is comprehensively studied. The as-fabricated p-i-n PSCs with pBTT, pBTTz, and pSNT as ETLs show the maximum photoconversion efficiencies of 12.8%, 14.4%, and 12.0%, respectively. To be highlighted, pBTTz-based device can maintain 80% of its stability after ten days due to its good hydrophobicity, which is further confirmed by a contact angle technique. More importantly, the pBTTz-based device shows a neglected hysteresis. This study reveals that the n-type polymers can be promising candidates as ETLs to approach solution-processed highly-efficient inverted PSCs.