Inorganic‐Sheet‐Templated Molecular Ordering in Layered Perovskites for Organic Field‐Effect Carrier Transport

Abstract

Layered halide perovskites are attractive materials for optoelectronic devices because of their highly ordered superlattice structures and tunable electronic properties. Here, we demonstrate a new transistor architecture in which the Pb–I inorganic framework of layered perovskites functions as a molecular ordering template for π‐conjugated organic semiconductor sheets. A layered perovskite, (BTBTA)2PbI4, is fabricated from a mixture of π‐conjugated 2‐(3‐ethylammonium)benzothieno[3,2‐b]benzothiophene hydroiodide (BTBTAI) and PbI2. X‐ray diffraction measurements reveal highly ordered layered structures with preferential in‐plane alignment induced by the Pb–I inorganic sheets. The spin‐coated (BTBTA)2PbI4 films exhibit p‐type field‐effect transistor characteristics with a hole mobility of 0.136 cm2 V−1 s−1. Electric‐field‐induced absorption spectroscopy, continuous‐wave photoinduced absorption spectroscopy, and energy‐level analysis demonstrate that hole accumulation predominantly occurs within the BTBTA‐derived organic sheets rather than within the Pb–I inorganic framework. Furthermore, laminated single‐crystal transistor devices exhibit significantly improved hole mobility reaching 1.90 cm2 V−1 s−1, indicating that grain boundaries in spin‐coated films limit carrier transport. These results demonstrate that layered inorganic frameworks can serve as crystallographic templating platforms for π‐conjugated organic semiconductors, enabling field‐effect hole transport through ordered organic sheets rather than through the inorganic Pb–I sheets themselves.