Highly Stable Hybrid Perovskite Solar Cells Modified with Polyethylenimine via Ionic Bonding

Abstract

Organic-inorganic hybrid perovskites are highly promising materials for photovoltaic applications, yet their rapid degradation remains a significant challenge. Here, three highly stable methylammonium lead iodide (MAPbI 3 ) perovskite films modified with polyethylenimines (PEIs) of different molecular weights (Mw = 600, Mw = 10000 and Mw = 70000) were successfully obtained. The PEIs were used as an additive in the perovskite to determine their influences on the structure, film quality, and performance of the perovskite. The perovskite films modified with PEIs showed excellent stability, when studied over 20 days under ambient air conditions with a medial humidity of 60%. The results of XRD, UV-Vis absorption and fluorescence lifetime measurements showed that the PEI could not substitute for MA within the perovskite crystal lattice. The solar power conversion efficiency (PCE) h of the pristine perovskite film and those modified with PEI (Mw = 600), PEI (Mw = 10000) and PEI (Mw = 70000) were 9.69%, 6.84%, 6.43% and 6.94%, respectively. Even though the PCE is lower for the PEI-modified solar cells, their stability is substantially improved. The improved stability is attributed to PEI-H + cations in the grain boundary of the perovskites, preventing them from direct contact with water molecules that otherwise cause fast degradation. This demonstrates that PEI modification is a simple and powerful strategy for stabilizing perovskite films.[a] Dr.

Electrode Engineering in Halide Perovskite Electronics: Plenty of Room at the Interfaces

“…Take PEIE as an example, the abundant amino and imine groups in PEIE tend to be protonated and make the terminal domains positively charged, which can bond with halide ions of perovskite and strengthen the film uniformity and compactness. [245] Under bottom-contact conditions, the implementation of SAMs can also modify the perovskite growth at the contact region, which is similar to the observation in OSC-based electronics. [246][247] Generally, the crystallinity of the resulting thin film highly depends on the affinity of SAM's terminal group to the perovskite.…”

State of the Art and Prospects for Halide Perovskite Nanocrystals

“…For example, butylphosphonic acid 4-ammonium chloride with a combination of phosphate and amino functional groups can simultaneously passivate MA + , Pb 2+ , and I – defects . Additionally, suaraine, polyaniline, and quaternary ammonium salts have been shown to be good capping ligands for MAPbI 3 bulk, MAPbI 3 film, and MAPbBr 3 bulk, respectively. , Peptides containing both −NH 3 + – and −COO – – in one molecule have been used to passivate MA + , Pb 2+ , and Br – of MAPbBr 3 perovskite NCs . Similarly, trifunctional l -cysteine has been used to passivate MAPbBr 3 perovskite NCs and induced self-assembly of perovskite NCs, based on synergistic effects among −NH 3 + –, −COO – –, and −SH– groups .…”

A hysteresis-free perovskite transistor with exceptional stability through molecular cross-linking and amine-based surface passivation

“…Indeed, it has been previously demonstrated that PEIE can effectively modify the surface of perovskites by forming strong hydrogen bonding interactions with surface defects. 47 Fig. 3e and f present the hole and electron transfer characteristics of the DPP-modified and PEIE surface treated perovskite FET where complete elimination of hysteresis is observed.…”