The application of organic–inorganic perovskites has recently attracted increasing interest due to their excellent optoelectronic properties. As an emerging semiconductor, the doping capability and efficiency of these materials require further clarification but have rarely been studied previously. In this study, diverse monovalent cations, Cu+, Na+, and Ag+, are incorporated into phenethylammonium tin iodide ((PEA)2SnI4) perovskite, and the resultant lattice structural variation, film properties, and thin-film transistor performance are systematically investigated by combining theoretical and experimental methods. Owing to their unique composition and octahedral unit, perovskite semiconductors possess strong ‘substitution doping tolerance’ with the aliovalent cation dopants. Theoretical studies claim that the hypothetical monovalent cation substitution on the Sn2+ B-site creates undesired vacancies and destabilizes the perovskite lattice structure. The experimental results show that the incorporated foreign aliovalent cations are not doped inside the perovskite lattice but segregated along the grain boundaries. Benefiting from the excellent hole transport property and passivation effect of copper iodide (CuI), the CuI–(PEA)2SnI4 heterostructure composite channel layers exhibit much improved film properties and device performance, including doubled field effect mobility, compared with the pristine ones.

Perovskite materials have displayed remarkable performance when used in photovoltaic devices. In comparison, research on their application in thin-film transistors (TFTs) has been developing slowly. We report reliable high-performance p-channel lead-free layered perovskite phenethylammonium tin iodide TFTs using simple and easily repeatable one-step spin-coating with premixed binary solvents of N,N-dimethylformamide (DMF) and chlorobenzene (CB)/ethyl acetate (EA). CB/EA antisolvent addition facilitates nucleation and formation of films with oriented grain ripening and full coverage. The champion perovskite TFT shows a fivefold increase in the mobility (3.8 cm 2 V −1 s −1 ) and a twofold magnitude increase in the current on/off ratio (∼10 6 ) with improved bias stress stability. Using well-developed n-channel indium gallium zinc oxide TFTs, a complementary inverter with a high gain of ∼30 is demonstrated. Moreover, with efficient charge transport, transistor amplification function, and pronounced photogating properties, the optimized perovskite phototransistors show a remarkably high photodetectivity of up to 3.2 × 10 17 Jones. This simple and highly repeatable method has attracted more attention for fabricating printed high-performance perovskite TFTs and phototransistors beyond energy sector applications.

Two-dimensional metal halide perovskites (2D MHPs) are promising candidates for transistor channel materials because of their high mobility in the lateral direction; however, Snbased 2D MHPs exhibit poor film quality and oxidation stability.Here, we report a simple method to improve the performance and stability of 2D MHP transistors by incorporating sodium iodide (NaI) additives. By adding 1 vol % NaI (Na1), the transistors with phenethylammonium tin iodide (PEA 2 SnI 4 ) exhibited reduced dual-sweep hysteresis, robust bias stability, and larger hole mobility (2.13 cm 2 V −1 s −1 ) than that of a pristine device (0.39 cm 2 V −1 s −1 ). Improvements in the film quality, such as increased grain size, crystallinity, and better film coverage, were observed in the PEA 2 SnI 4 :NaI film. In addition, NaI effectively passivated the iodine vacancies at the grain boundaries, thereby suppressing the defects.

Organic semiconductors (OSCs) are promising sensing materials for printed flexible gas sensors. However, OSCs are unstable in the humid air, which limits the realization of gas sensors for multiple usages. In this paper, we report a facile and effective way to improve the air stability of an OSC film to realize multiple reversibly used printed gas sensors by adding molecular additives. The tetracyanoquinodimethane (TCNQ) or 4-aminobenzonitrile (ABN) additives effectively prevent adsorption of moisture from the air on the OSC layer, thereby providing a stable gas sensor operation. The organic field-effect transistor (OFET)-based indacenodithiophene-co-benzothiadiazole with TCNQ or ABN shows highly reliable ammonia (NH 3 ) gas sensing up to 10 ppm in air, with 23.14% sensitivity, and the gas sensor signal can recover up to 100%. In particular, the stability of gas detection is greatly improved by the additives, which can be performed in the air for 16 days. The result indicates that the elimination of moisture trapped in OSCs with molecule additives is critical in the improvement of device air/operational stabilities and the achievement of highperformance OFET-based gas sensors.

Metal halide perovskites have attracted a considerable amount of research attention with significant progress made in the field of optoelectronics. Despite their outstanding electrical characteristics, structural defects impede their potential performance due to the polycrystalline nature of solution‐processed perovskite films. Herein, the effective p‐type doping and defect passivation of phenethylammonium tin iodide ((PEA)2SnI4) perovskite films using xanthate additives as a sulfur source is reported. Sulfur can be introduced to the iodine vacancies mainly at the grain boundaries of the perovskite film, passivating the electrical defects originating from the iodine vacancy and increasing the hole concentration. The Fermi‐level shift toward the valence band maximum of the sulfur‐doped perovskite film is confirmed using ultraviolet photoemission spectroscopy, resulting in p‐type doping. Finally, the electrical performance improvement for the 0.2% sulfur‐doped (PEA)2SnI4 thin‐film transistor with a mobility of 1.45 cm2 V−1 s−1, an on/off ratio of 2.9 × 105 is demonstrated, and hysteresis of 10 V is reduced.