Monodisperse Carbon Nitride Nanosheets as Multifunctional Additives for Efficient and Durable Perovskite Solar Cells

Abstract

Two-dimensional (2D) materials are promising components for defect passivation of metal halide perovskites. Unfortunately, commonly used polydisperse liquid-exfoliated 2D materials generally suffer from heterogeneous structures and properties while incorporated into perovskite films. We introduce monodisperse multifunctional 2D crystalline carbon nitride, poly­(triazine imide) (PTI), as an effective defect passivation agent in perovskite films via typical solution processing. Incorporation of PTI into perovskite film can be readily attained by simple solution mixing of PTI dispersions with perovskite precursor solutions, resulting in the highly selective distribution of PTI localized at the defective crystal grain boundaries and layer interfaces in the functional perovskite layer. Several chemical, optical, and electronic characterizations, in conjunction with density functional theory calculations, reveal multiple beneficial roles from PTI: passivation of undercoordinated organic cations at the surface of perovskite crystal, suppression of ion migration by blocking diffusion channels, and prevention of hole quenching at perovskite/SnO2 interfaces. Consequently, a noticeably improved power conversion efficiency is achieved in perovskite solar cells, accompanied with promoted stability under humid air and thermal stress. Our strategy highlights the potential of judiciously designed 2D materials as a simple-to-implement material for various optoelectronic devices, including solar cells, based on hybrid perovskites.

Ultrathin Carbon Nitride Nanosheets with Fast Interlayer Charge Transfer: Toward Perovskite Solar Cells

“…The interaction between CN nanosheets and PVK was further elucidated by FTIR; the FTIR spectra of PVK and PVK/CN nanosheets are shown in Figure e,f. The characteristic absorption bands are observed at 1635 cm –1 from PVK/CN nanosheets, which can be assigned to the vibration modes of CN bonds from organic cations . Compared with PVK, the PVK/CN nanosheets showed the bending vibration peak of the N–H bond in the amino group shifted from 1633 to 1652 cm –1 , and the stretching vibration peak of the N–H bond moved from 3445 to 3432 cm –1 .…”

Functional Carbon Nitride Materials in Photo‐Fenton‐Like Catalysis for Environmental Remediation

“…[35] Up till now, functional carbon nitride has been employed in wide solar-driven applications, such as air purification, [36,37] energy conversion [38][39][40] and storage. [41,42] For examples, CN nanosheets were used for efficient photocatalytic NO removal [36] and perovskite solar cells. [42] In addition, CN-based heterostructures, such as van der Waals [43] and Z-scheme [44] heterojunctions, were widely developed for photocatalytic water splitting.…”

“…[41,42] For examples, CN nanosheets were used for efficient photocatalytic NO removal [36] and perovskite solar cells. [42] In addition, CN-based heterostructures, such as van der Waals [43] and Z-scheme [44] heterojunctions, were widely developed for photocatalytic water splitting.…”

Enhancing operational stability in perovskite solar cells by solvent-free encapsulation method

“…[22][23][24][25] For that, many interfacial materials have been investigated, including metal oxides, 26 polymers, 27 and carbon-based materials. 28 As an example of this approach, the use of phenethylammonium iodide (PEAI) as a passivating agent, reduces the trap density (1.53 Â 10 15 cm À3 ) compared to the control sample (2.78 Â 10 15 cm À3 ). 29 A seminal work presented by Grancini et al 30 created a 2D/3D interface with a protonated salt of aminovaleric acid iodide (AVAI) that protects perovskite against moisture, improving the long-term stability of the cell under illumination for one year at 55 C. Regarding HTMs, employing uorinated compounds such as Spiro-mF and Spiro-oF (uorinated analogues of Spiro-OMeTAD) have favourable shiing of the electronic state for hole extraction.…”