Decorating hole transport material with −CF_(3) groups for highly efficient and stable perovskite solar cells

The hole transport material (HTM) plays an extremely important role to determine the power conversion efficiency (PCE) and the stability of perovskite solar cells (PSCs). Herein, we report an effective strategy to improve the performance of HTMs by introducing −CF_(3) groups via the rational decorative mode. Upon direct attachment or nonconjugated alkoxyl bridging of −CF_(3) groups on the terminal diphenylamines, the resulting molecular HTMs, i.e., 2,7-BCzA4CF_(3) and 2,7-BCzA4OCCF_(3), show distinct properties. Compared with 2,7-BCzA4CF_(3), the nonconjugated alkoxyl bridging −CF_(3) group-based 2,7-BCzA4OCCF_(3) exhibits better thermal stability, hydrophobicity, and a dramatically upgraded hole mobility by 135.7-fold of magnitude to 1.71 × 10^(−4) cm^(2) V^(−1) S^(−1). The PSCs with 2,7-BCzA4OCCF_(3) as HTM exhibit an PCE of up to 20.53% and excellent long-term stability, maintaining 92.57% of their performance for 30 days in air with humidity of 30% without encapsulation. This work provides beneficial guidelines for the design of new HTMs for efficient and stable PSCs.

First-principles investigation of chemical modification on two-dimensional iron-phthalocyanine sheet

Successful synthesis of single iron-phthalocyanie （FePc） framework layer on substrate and its transferrable properties open the door for decorating the separately distributed transition metals for exploring the diverse properties. We have studied the effects of chemical modification on two-dimensional FePc organometallic framework with density functional theory. For simplicity, the non-metal atoms with variant valence electrons are used as prototypes to estimate the effects ＆ore chemical modifications with different functional groups. The thermo-stabilities of the non-metal atom decorated complex sheet materials have been estimated by the first-principles constant energy molecular dynamic simulations. Upon the non- metal atom adsorption, the magnetic moment could be changed from 2 ~tB to 0, 1, 2, and 3 ~tB per unit cell for the case of tetra-, penta-, hexa-, and hepta-valent non-metal modifications, respectively, showing interesting promise to tailor its magnetic properties for potential applications.