Snaith group

Abstract:

Interfacial materials tend to alter the crystallization, films growth and defect formation process of the as‐deposited perovskites, which has been a critical and fundamental factor in determining the efficiency and operational stability of perovskite‐based optoelectronic devices. This review explores the underlying mechanism of interfacial reactions, which can either result in degradations or be beneficial. The influence of interfacial reactions, mainly interface‐induced deprotonation of organic cations and amidation processes, are discussed in relation to their impact on perovskite film growth and ensuing optoelectronic device performance. It is further proposed strategies to regulate these reactions and mitigate their negative effects to achieve high performance optoelectronic devices.

Abstract:

While (111)-dominated perovskite films hold the potential for high-stability solar cells, most studies have primarily focused on modulating the (111) facets, overlooking the distribution and formation mechanism of the nondominant (100) facets. In this study, we delve into the (111) orientation via solvent regulation and investigate the evolution of facet distribution using various diffraction techniques. The findings reveal that simply stacking (111) facets does not inherently enhance solar cells. Instead, the distribution of nondominant (100) facets in (111)-dominated films significantly influences both photoelectric property and stability. These observations highlight the critical need to manage the interplay between dominant and nondominant facets. The study further offers strategies for addressing facet heterogeneity to achieve a uniform facet distribution. This research provides a comprehensive framework for understanding (111)-dominated perovskites and offers valuable guidance for designing high-performance perovskite solar cells.

Abstract:

Reducing heterointerface nonradiative recombination is a key challenge for realizing highly efficient perovskite solar cells (PSCs). Motivated by this, a facile strategy is developed via interfacial energetics reversal to functionalize perovskite heterointerface. A surfactant molecule, trichloro[3-(pentafluorophenyl)propyl]silane (TPFS) reverses perovskite surface energetics from intrinsic n-type to p-type, evidently demonstrated by ultraviolet and inverse photoelectron spectroscopies. The reconstructed perovskite surface energetics match well with the upper deposited hole transport layer, realizing an exquisite energy level alignment for accelerating hole extraction across the heterointerface. Meanwhile, TPFS further diminishes surface defect density. As a result, this cooperative strategy leads to greatly minimized nonradiative recombination. PSCs achieve an impressive power conversion efficiency of 25.9% with excellent reproducibility, and a nonradiative recombination-induced qV_oc loss of only 57 meV, which is the smallest reported to date in n-i-p structured PSCs.