Bifunctional Effects of Trichloro(octyl)silane Modification on the Performance and Stability of a Perovskite Solar Cell via Microscopic Characterization Techniques

Abstract

Passivation by small organic compounds can reduce the trap density and enhance the humidity and illumination stability of perovskite solar cells (PSCs). However, the small molecule passivated on the perovskite film cannot endure harsh heat stress. Herein, we find that the trichloro(octyl)silane (TC-silane) is an excellent candidate to modify the perovskite surface and grain boundary nondestructively through the formation of a heat-resistive silicone layer, leading to a comprehensive improvement of efficiency and stability with low cost as well as facile fabrication. The silane is a type of solvent and can be upscaled by a solution process in the device. TC-silicone can cross-link the grain boundaries through hydrolytic condensation. The cross-linking silicone can resist the moisture and heat stresses to enhance the stability. Also, microphotoluminescence reveals that TC-silane treatment can passivate the perovskite film and enhance the optoelectronic properties through chloride replenishment by releasing a hydrogen chloride molecule in the hydrolytic reaction. By utilizing Kevin probe force microscopy, we further uncover that TC-silane forms a dipole layer to facilitate the charge separation. TC-silane passivated PSCs deliver a champion efficiency of 20.03% and remain at 80% of their initial efficiency for more than 800 h at 70−80% relative humidity in air and for about 80 h under 85 °C thermal stress without encapsulation.

Color‐Stable Deep‐Blue Perovskite Light‐Emitting Diodes Based on Organotrichlorosilane Post‐Treatment

“…Silane-based materials have been used to stabilize perovskite solar cells to improve the moisture and heat stress resistance of perovskites. [21][22][23] For R-SiCl 3 , reports show that its hydrolysis releases HCl, after which R-SiCl 3 crosslinks with itself. The HCl diffuses into the perovskite film and further interacts with the perovskite via halide anion exchange (e.g., Br − in perovskite with Cl − in HCl) to form a mixed halide perovskite, [18,21,24] which can be described by the following equations:…”

Cascade Type‐II 2D/3D Perovskite Heterojunctions for Enhanced Stability and Photovoltaic Efficiency

“…As shown in Figure 4c,d, the potential electrical mapping by Kelvin probe force microscope (KPFM) indicates that the NMABr passivation improves the average potential of the perovskite films from 1.82 to 1.87 V (corresponding to the tip potential), which is suitable for the hole transport. [ 26 ] To make it more specific, we give the line scan of KFPM images and get the surface potential plots across the grain boundaries (Figure S6, Supporting Information). We can see that the highest potential of NMABr‐passivated perovskite film (2.085 V) is 0.052 V higher than that of pristine perovskite film (2.033 V), which are all located around at the middle of grain crystals.…”

Passivation and process engineering approaches of halide perovskite films for high efficiency and stability perovskite solar cells

“…Trichloro(octyl)silane (TC-silane) modified the perovskite surface and passivated film GBs through cross-linking and forming a heat-resistive silicone layer, leading to a comprehensive improvement of PSC efficiency and stability against moisture and heat. 219 TCsilane passivated PSCs delivered a PCE of 20.03% with only a 20% loss after more than 800 h at ~75% RH in air and about 80 h under 85 °C thermal stress.…”