Perovskites have been intensively investigated for their use in solar cells and light‐emitting diodes. However, research on their applications in thin‐film transistors (TFTs) has drawn less attention despite their high intrinsic charge carrier mobility. In this study, the universal approaches for high‐performance and reliable p‐channel lead‐free phenethylammonium tin iodide TFTs are reported. These include self‐passivation for grain boundary by excess phenethylammonium iodide, grain crystallization control by adduct, and iodide vacancy passivation through oxygen treatment. It is found that the grain boundary passivation can increase TFT reproducibility and reliability, and the grain size enlargement can hike the TFT performance, thus, enabling the first perovskite‐based complementary inverter demonstration with n‐channel indium gallium zinc oxide TFTs. The inverter exhibits a high gain over 30 with an excellent noise margin. This work aims to provide widely applicable and repeatable methods to make the gate more open for intensive efforts toward high‐performance printed perovskite TFTs.
Despite the impressive development of metal halide perovskites in diverse optoelectronics, progress on high-performance transistors employing state-of-the-art perovskite channels has been limited due to ion migration and large organic spacer isolation. Herein, we report high-performance hysteresis-free p-channel perovskite thin-film transistors (TFTs) based on methylammonium tin iodide (MASnI3) and rationalise the effects of halide (I/Br/Cl) anion engineering on film quality improvement and tin/iodine vacancy suppression, realising high hole mobilities of 20 cm2 V−1 s−1, current on/off ratios exceeding 107, and threshold voltages of 0 V along with high operational stabilities and reproducibilities. We reveal ion migration has a negligible contribution to the hysteresis of Sn-based perovskite TFTs; instead, minority carrier trapping is the primary cause. Finally, we integrate the perovskite TFTs with commercialised n-channel indium gallium zinc oxide TFTs on a single chip to construct high-gain complementary inverters, facilitating the development of halide perovskite semiconductors for printable electronics and circuits.
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.
The development of transparent and high‐performance p‐type semiconductors as a counterpart of n‐type metal oxide semiconductors has attracted significant interest for the integration of complementary circuits and p–n junction devices. This study investigates the effect of trace O2 for high‐performance and solution‐processed inorganic p‐channel Zn‐doped copper iodide (CuI) thin‐film transistors (TFTs) via a combined computation–experiment approach. The absorbed O2 molecules in the CuI film can occupy iodine vacancies, acting as trap passivator. Meanwhile, the strong electronegativity of O2 enables electron capture from the CuI matrix, leading to p‐doping. Trace O2‐treated Zn‐doped CuI TFTs exhibit significantly improved electrical performance compared to untreated devices. Optimized TFTs exhibit a high field‐effect hole mobility of 4.4 cm2 V−1 s−1, high on/off current ratio of ≈107, and small hysteresis. These findings provide a clear basis for realizing reproducible and high‐performance metal‐halide (e.g., CuI and perovskite) optoelectronic devices using low‐cost solution process.
Pseudo-capacitive negative electrodes remain a major bottleneck in the development of supercapacitor devices with high energy density because the electric double-layer capacitance of the negative electrodes does not match the pseudocapacitance of the corresponding positive electrodes. In the present study, a strategically improved Ni-Co-Mo sulfide is demonstrated to be a promising candidate for high energy density supercapattery devices due to its sustained pseudocapacitive charge storage mechanism. The pseudocapacitive behavior is enhanced when operating under a high current through the addition of a classical Schottky junction next to the electrode–electrolyte interface using atomic layer deposition. The Schottky junction accelerates and decelerates the diffusion of OH‒/K+ ions during the charging and discharging processes, respectively, to improve the pseudocapacitive behavior. The resulting pseudocapacitive negative electrodes exhibits a specific capacity of 2,114 C g−1 at 2 A g−1 matches almost that of the positive electrode’s 2,795 C g−1 at 3 A g−1. As a result, with the equivalent contribution from the positive and negative electrodes, an energy density of 236.1 Wh kg−1 is achieved at a power density of 921.9 W kg−1 with a total active mass of 15 mg cm−2. This strategy demonstrates the possibility of producing supercapacitors that adapt well to the supercapattery zone of a Ragone plot and that are equal to batteries in terms of energy density, thus, offering a route for further advances in electrochemical energy storage and conversion processes.
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