Enhanced Device Performances of MAFACsPb(I_xBr_1–x) Perovskite Solar Cells with Dual-Functional 2-Chloroethyl Acrylate Additives

Abstract

Perovskite photovoltaics (PePVs) tend to suffer from a high density of defects that restrict the device in terms of performances and stability. Therefore, defect passivation and film-quality improvement of perovskite active layers are crucial for highperformance PePVs. In this work, 2-chloroethyl acrylate (CEA) with CO and −Cl groups in Cs 0.175 FA 0.750 MA 0.075 Pb (I 0.880 Br 0.120 ) precursor solutions is introduced as a novel bifunctional additive to act as both a defect passivator and perovskite-growth controller. With the aid of CEA, the perovskite crystallinity and average grain size are improved, and perovskite defects are effectively reduced, thus increasing the representative efficiency (PCE = 19.32%). PePVs with CEA also maintain their initial efficiency of 85% even after about 500 h under air conditions with a humidity of 40 ± 5%. As a result, this study proves that the novel additive CEA can produce higher PePV efficiency and more stable devices.

Potassium Salt Coordination Induced Ion Migration Inhibition and Defect Passivation for High-Efficiency Perovskite Solar Cells

“…Because of the excellent photovoltaic properties such as long carrier diffusion length, high carrier mobility, low exciton binding energy, and high absorbance, perovskites have been widely studied as the light absorption material of solar cells. − In the past decade, the certified power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been promoted from 3.8 to 25.7% . However, the disordered trap states distributed in the perovskites seriously impair the PCE of PSCs, whereas the cation and anion defects such as uncoordinated Pb 2+ , uncoordinated I – , and a Pb–I antisite capture charge carriers. − Trap states at grain boundaries not only act as the carrier recombination center, inducing nonradiative recombination and contributing to the major loss mechanism, but also result in the rapid decomposition of a polycrystalline perovskite as the channels for the diffusion of moisture and oxygen, causing the PCE degradation. − In addition, due to the iodide Frenkel defect caused by ion migration of I – , PSCs cannot reach the maximum power output immediately under illumination, known as the hysteresis of PSCs …”

Tailoring p-Type Charge-Transfer-Doped Hole Transport Layer for All-Inorganic CsPbBr3 Perovskite Solar Cells

“…Compared to CsPbBr 3 , the binding energy of Pb 4f 7/2 in CsPbBr 3 /NiO-Cys changed from 138.14 to 138.04 eV, while that of Pb 4f 5/2 decreased from 142.95 to 142.87 eV (high-resolution graphs in Figure 1f). 32,33 According to the lower binding energy of Pb 4f, the lone pair of electrons of the S or N elements of Cys interacts with the CsPbBr 3 lattice. The peak of S 2p at 158.7 eV in Figure 1g is attributed to the Pb−S bond.…”

Orotic Acid as a Bifunctional Additive for Regulating Crystallization and Passivating Defects toward High-Performance Formamidinium–Cesium Perovskite Solar Cells

“…Apart from the small molecular additives possessing a single function, a variety of bifunctional or multiple functional additives have been reported recently. − In many cases, they contain both a cation and an anion part with each playing a different role. Cations like ammonium (−NH 3 + ) groups tend to passivate negative defects by electrostatic interactions or can be embedded into the perovskite lattice to form low-dimensional perovskites. , Anions like SCN – play an important role in overcoming growth challenges and reducing halide vacancies .…”