Tailoring the Interfacial Termination via Dipole Interlayer for High‐Efficiency Perovskite Solar Cells

Abstract

The ionic nature of the organic‐inorganic hybrid perovskite material is prone to react with different functional groups. Here, a series of polar molecules with permanent dipole moments are designed to modify the perovskite surface termination. It is observed that proper interfacial design can significantly reduce trap state density for effective charge transfer. The energy level of the substrate can be adjusted by the magnitude and direction of the dipole moment. As a result, a high 24.54% photo‐electric conversion efficiency is reached by introducing pentafluoride benzene moieties with carboxylic functional groups. In addition, the humidity and heat stability of the perovskite device is obviously improved. This work demonstrates the importance of chemical interactions at perovskite termination and paves the way for further enhancing the performance of perovskite solar cells.

Modulation of Perovskite Surface Energetics for State‐of‐the‐Art Solar Cells

“…[ 88,89 ] Recently, numerous works demonstrated the feasibility and high effectiveness of surface dipole on perovskite layer with multiple functionalities such as tuning surface energetics, reducing surface defects, and enhancing stability. [ 90–93 ]…”

“…perovskite layer with multiple functionalities such as tuning surface energetics, reducing surface defects, and enhancing stability. [90][91][92][93] The work function of perovskite surface can be finely tuned in terms of both magnitude and direction by the dictation of surface dipole. For example, Canil et al reported a controllable shift over several hundreds of meV for perovskite work function by managing surface dipole coverage.…”

Molecular dipole engineering-assisted strain release for mechanically robust flexible perovskite solar cells

“…24 Liu et al demonstrated that the dipole moment of additives has a positive effect in reducing trap state density. 25 Pang et al confirmed the importance of molecular dipoles in amplifying the passivation effect of additive molecules. Moreover, Yang et al showed that the ligand intrinsic dipole moment and a charge-density displacement by ligand–surface interactions and bond formation can affect the work function change.…”

Bifunctional Hole-Transport Materials with Modification and Passivation Effect for High-Performance Inverted Perovskite Solar Cells

“…The methods to improve the efficiency of PSC devices include controlling perovskite crystal growth, interface modification, and innovative optimization of charge transport layers. − The traditional HTM used in p – i – n devices is PTAA. However, PTAA as a polymer, its complex synthesis process and purification process, leading to the expensive price, and the poor synthesis repeatability also seriously restrict the device commercialization. , It is reported that the organic small-molecule HTMs can not only transport holes but can also form self-assembled monolayers on ITO or passivate the perovskites to significantly reduce nonradiative recombination, generating a PCE of the inverted device as high as 25.4%. − Therefore, organic small-molecule HTMs are ideal candidates due to their simple synthesis, clear structure, and ability to further interact with ITO or perovskite through specific element groups, which can passivate the interface contact and reduce radiative recombination. − However, organic small-molecule HTMs that can interact with both ITO and perovskite in inverted PSCs are rarely reported.…”