Besides 3D hybrid perovskites (HP), Ruddlesden-Popper (RP) phase low-dimensional HPs have gained huge research attention owing to their higher long-term stability and suppressed ion migration. However, their strong quantum confinement effects limit optoelectronic properties. These drawbacks diminish in higher-n structures with enhanced charge transfer. Thus, high photodetection performance was always obtained at higher n number structure as the charge transfer improves when n increase. The quasi-2D HPs display high photoresponsivity, good detectivity and fast switching time accompanied by better device stability [1], [2]. To enhance charge transfer, graphite or graphene can be used to improve conductivity and stability owing to their thermostability and hydrophobicity. Additionally, their layered structure affinity could favour interactions with RP HPs, enhancing device performance. For large-area photodetectors and industrial processing, large amounts and high-quality HPs are often required. Mechanosynthesis (MS) is a promising technique to produce quickly large quantities of high-quality powder as an eco-friendly alternative for HP synthesis [3], [4].

In this work, we present the successful MS of low dimensional HPs: n= 1, 2, 3 HPs with three different organic ammonium cation spacers (n-butylammonium: BA; n-hexylammonium: HA and 2-phenylethylammonium: PEA) and their composites with 5 wt% graphite. To the best of our knowledge, it is the first time that the MS of the as-mentioned quasi-2D HPs and graphite composite was realized. These powders have been then compacted into wafers and photodetection measurements have been performed. The photoconducting behaviors evidenced an improved photoresponse in PEA⁺-based HPs and composites by comparison with other HPs phases. The comparison of microstructural and optical properties of powder and wafers after compaction showed that compaction pressure impacted grain size, crystallite preferential orientation, and phase evolution in 2D HPs. However, above all, PL results reveal that compaction enables reduced reabsorption effects, allowing an enhanced surface emission, possibly attributed to the preferential grain orientation and lattice distortion. The compaction studies on n=2 BA⁺- and PEA⁺-based composites with 5 wt% graphite further confirm again the compaction-enhanced in-plane orientation and improved graphite integration with PEA⁺ in quasi-2D HPs due to structural affinity and π- π interactions among aromatic rings and graphite. Therefore, the n=2 PEA⁺-based wafer devices show improved charge transfer due to better-connected PbI₆ frameworks and π-π interactions, which are further enhanced by adding 5 wt% graphite. The PEA⁺-based low dimensional HPs was shown to be a promising potential candidate for photodetection, especially its composite with graphite. This study offers a full picture into MS low-dimensional HPs and their graphite composites for photodetection, exploring the understanding of powder-compatible devices.