Hybrid phototransistors based on InGaZnO (IGZO) metal oxide thin-film transistors (TFT) and a photoabsorbing capping layer such as perovskite (MAPbI 3 ) are a promising low-cost device for developing advanced X-ray and UV flat-panel imagers. However, it is found that the introduction of MAPbI 3 inevitably damages the IGZO channel layer during fabrication, leading to deteriorated TFT characteristics such as off-current rising and threshold voltage shift. Here, we report an effective approach for improving the performance of the perovskite−IGZO phototransistor by inserting a [6,6]-phenyl C61-butyric acid methyl ester (PCBM) or PCBM:PMMA interlayer between the patterned MAPbI 3 and IGZO. The interlayer effectively prevents the IGZO from damage by the perovskite fabrication process, while allowing efficient charge transfer for photosensing. In this configuration, we have achieved a high-detectivity (1.35 × 10 12 Jones) perovskite−IGZO phototransistor with suppressed off-state drain current (∼10 pA) in the dark. This work points out the importance of interface engineering for realizing higher performance and reliable heterogeneous phototransistors.

features for developing high-performance X-ray imagers and ultraviolet sensors. [3] For imaging application, IGZO TFTs were mainly integrated with amorphous silicon and organic photodiodes, [3c,e,4] the spectral of which were usually limited to visible light detection. Large-area, active-matrix infrared sensing, therefore, remains a challenge.Organic-inorganic hybrid perovskites possess excellent optoelectronic properties with high absorption coefficient, high charge carrier mobility, long carrier diffusion lengths, and tunable bandgaps, [5] rendering it a promising material for across-the-board optoelectronic devices, [6] including photovoltaic cells, [7] light-emitting, lasing devices, [8] and high-performance photodetectors. [9] In particular, compared with predominant photodetectors made of inorganic semiconductors, solution-processable perovskite is more promising for lowcost, flexible, and large-area scenarios. [6d] Conventional lead-based perovskite photodiodes (PDs) provide a detection spectral range from 300 to 800 nm. [10] To further extend the spectral response to the near-infrared (NIR) range, there are normally two approaches. One is to combine perovskite with narrow bandgap polymers or quantum dots such as PDPP3T [11] and PbS quantum dots. [12] Another approach is to introduce an Sn-Pb binary perovskite PDs. [13] The smaller ionic radii of Sn 2+ than Pb 2+ (Sn 2+ :1.35 Å and Pb 2+ : 1.49 Å) [14] reduces the bandgap of perovskites due to the bowing effect, [15] so that Sn-Pb hybrid perovskite has lower bandgap to extend the light absorption to ≈1000 nm. Recently Xiaobao et al. reported MA 0.5 FA 0.5 Pb 0.5 Sn 0.5 I 3 perovskite photodetector, exhibiting a detectivity of over 10 12 Jones ranging from 800 to 970 nm. [13c] Wang et al. fabricated mixed Sn-Pb perovskite photodetectors with a broadband response from 300 to 1000 nm, responsivity (R) of over 0.4 A W −1 , and detectivity (D*) of over 10 12 Jones in the near-infrared region. [13b] Encouraging improvements in the Sn-Pb based perovskite stability have also been reported very recently, such as using GuaSCN passivation to achieve 1 µs carrier lifetime with long-term stability. [16] The above development of low bandgap organic-inorganic perovskite materials has brought new opportunity for developing advanced flat-panel Flat-panel imagers have wide applications in industrial and medical inspections. Nonetheless, large area infrared imaging remains a challenge due to the fact that the state-of-the-art infrared sensors are usually based on silicon or germanium technologies, which are limited by the wafer size. Recent advances in low bandgap Sn-Pb perovskite photodiodes (PDs) and indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) matrix backplane bring new opportunity for developing the large area near-infrared image sensor. As a proof of concept, a 12 × 12 pixels array with each pixel independently controlled by the gate voltage of a TFT are constructed. Arrays of Sn-Pb based perovskite PDs are spin deposited onto the IGZO TF...

Inorganic–organic hybrid perovskite thin films have attracted significant attention for developing new types of optoelectronic devices due to their superb optoelectronic properties. Herein, a hybrid phototransistor for near‐infrared (NIR) detection is constructed by capping a narrow bandgap Pb–Sn perovskite layer on top of an indium gallium zinc oxide (IGZO) thin‐film transistor (TFT), with a C60 interlayer acting as the electron transporting layer. The Pb–Sn perovskite layer is precisely spin patterned onto the IGZO TFTs' channel region via a hydrophobic perfluoro(1‐butenyl vinyl ether) (CYTOP) photolithography process. In this configuration, a high‐detectivity (2.24 × 1010 Jones at 900 nm) perovskite–C60–IGZO hybrid infrared phototransistor is achieved, and the narrow bandgap perovskite–IGZO hybrid phototransistor has a sensitive photoresponse down to 1100 nm.

Indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) exhibit high field-effect carrier mobility and low off-state current, which are attractive for high speed and low noise photodetectors and image sensor applications. However, with an optical band gap of ∼3.3 eV, the photodetection range of IGZO TFTs is limited to short wavelength ultraviolet (UV) light.Here, we demonstrate a simple approach to enhance the performance of IGZO-based phototransistors by incorporating layers of solution-processed perovskite quantum dots (QDs) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Owing to the fast transfer of photogenerated electrons by CsPbBr 3 QDs absorbing layer, the photoresponse of QD-decorated IGZO phototransistor is extended to the visible range (500 nm), and the responsivity and detectivity of QD-decorated device are more than two order higher than those of original IGZO TFTs. Moreover, the QD-decorated IGZO phototransistor also exhibits enhanced performance under UV light (350 nm), achieving a responsivity of 9.72 A W −1 , a detectivity of 2.96×10 12 Jones, and a light to dark current ratio in the order of 10 6 at a wavelength of 350 nm (a light intensity of 207.3 μW cm −2 ).

Schottky photodiodes, which are based on metal-semiconductor junctions, are one of the most widely used technologies for low cost image sensor arrays. Here, we fabricate a hole transport layer free organolead halide perovskite diode (ITO/CH 3 NH 3 PbI 3 /PCBM/BCP/Ag), and explore its Schottky diode behavior. A Schottky barrier is identified between the transparent conductor ITO and the solution processed perovskite (CH 3 NH 3 PbI 3 ), with a barrier height of ∼0.97 eV measured by capacitance-voltage (C-V) measurements. The Schottky barrier at the ITO/CH 3 NH 3 PbI 3 junction is found to effectively suppress electron injection from ITO to the perovskite under reversed bias, leading to a surprising low dark current of 1.9×10 −9 A cm −2 when biased at −0.1 V. When functioning as a photodetector, the ITO/CH 3 NH 3 PbI 3 Schottky diode outperforms the conventional perovskite photodiode with PEDOT:PSS layer in terms of detectivity, reaching a high specific detectivity (D * ) of 8.9×10 12 Jones. Moreover, by tuning the band gap of perovskite with the content of bromine (Br), i.e. CH 3 NH 3 Pb (I 1−X Br X ) 3 (0x1), the Schottky barrier height at the ITO/perovskite junction is raised, further lowering the dark current of the perovskite photodiode. This work provides fundamental investigation on the device physics of the perovskite Schottky diode, as well as a low cost approach for designing the high sensitivity of photodetectors.