Colloidal quantum dots (QDs) of lead halide perovskite have recently received great attention owing to their remarkable performances in optoelectronic applications. However, their wide applications are hindered from toxic lead element, which is not environment- and consumer-friendly. Herein, we utilized heterovalent substitution of divalent lead (Pb) with trivalent antimony (Sb) to synthesize stable and brightly luminescent CsSbBr QDs. The lead-free, full-inorganic QDs were fabricated by a modified ligand-assisted reprecipitation strategy. A photoluminescence quantum yield (PLQY) was determined to be 46% at 410 nm, which was superior to that of other reported halide perovskite QDs. The PL enhancement mechanism was unraveled by surface composition derived quantum-well band structure and their large exciton binding energy. The Br-rich surface and the observed 530 meV exciton binding energy were proposed to guarantee the efficient radiative recombination. In addition, we can also tune the inorganic perovskite QD (CsSbX) emission wavelength from 370 to 560 nm via anion exchange reactions. The developed full-inorganic lead-free Sb-perovskite QDs with high PLQY and stable emission promise great potential for efficient emission candidates.

Photodetectors convert light signals into current or voltage outputs and are widely used for imaging, sensing, and spectroscopy. Perovskite-based photodetectors have shown high sensitivity and fast response due to the unprecedented low recombination loss in this solution processed semiconductor. Among various types of CHNHPbI morphology (film, single crystal, nanowire), single-crystalline CHNHPbI nanowires are particularly interesting for photodetection because of their reduced grain boundary, morphological anisotropy, and excellent mechanical flexibility. The concomitant disadvantage associated with the CHNHPbI nanowire photodetectors is their large surface area, which catalyzes carrier recombination and material decomposition, thus significantly degrading device performance and stability. Here we solved this key problem by introducing oleic acid soaking to passivate surface defects of CHNHPbI nanowires, which leads to a device with much improved stability and unprecedented sensitivity (measured detectivity of 2 × 10 Jones). By taking advantage of their one-dimensional geometry, we also showcased, for the first time, the linear dichroic photodetection of our CHNHPbI nanowire photodetector.

Organolead triiodide perovskite (CH3NH3PbI3) as a light-sensitive material has attracted extensive attention in optoelectronics. The reported perovskite photodetectors (PDs) mainly focus on the individual, which limits their spatial imaging applications. Uniform perovskite networks combining transparency and device performance were synthesized on poly(ethylene terephthalate) (PET) by controlling perovskite crystallization. Photodetector arrays based on above network were fabricated to demonstrate the potential for image mapping. The trade-off between the PD performance and transparency was systematically investigated and the optimal device was obtained from 30 wt % precursor concentration. The switching ratio, normalized detectivity, and equivalent dark current derived shot noise as the critical parameters of PD arrays reached 300, 1.02 × 10(12) Jones, and 4.73 × 10(-15)A Hz(-1/2), respectively. Furthermore, the PD arrays could clearly detect spatial light intensity distribution, thus demonstrating its preliminary imaging function. The perovskite network PD arrays fabricated on PET substrates could also conduct superior flexibility under wide angle and large number of bending. For the common problem of perovskite optoelectronics in stability, the perovskite networks sheathed with hydrophobic polymers greatly enhanced the device stability due to the improved interface contacts, surface passivation, and moisture isolation. Taking into consideration transparency, flexibility, imaging and stability, the present PD arrays were expected to be widely applied in visualized portable optoelectronic system.

Organolead halide perovskites are becoming intriguing materials applied in optoelectronics. In the present work, organolead iodide perovskite (OIP) nanowires (NWs) have been fabricated by a one step self-assembly method. The controllable NW distributions were implemented by a series of facile techniques: monolayer and small diameter NWs were prepared by precursor concentration tuning; NW patterning was achieved via selected area treatment assisted by a mask; NW alignment was implemented by modified evaporation-induced self-assembly (EISA). The synthesized multifunctional NWs were further applied in photodetectors (PDs) and solar cells as application demos. The PD performances have reached 1.32 AW(-1) for responsivity, 2.5 × 10(12) Jones for detectivity and 0.3 ms for response speed, superior to OIP films and other typical inorganic NW based PD performances. An energy conversion efficiency of ∼2.5% has been obtained for NW film based solar cells. The facile fabrication process, controllable distribution and optoelectronic applications make the OIP NWs promising building blocks for future optoelectronics, especially for low dimensional devices.

The transitionmetal dichalcogenides‐based phototransistors have demonstrated high transport mobility but are limited to poor photoresponse, which greatly blocks their applications in optoelectronic fields. Here, light sensitive PbS colloidal quantum dots (QDs) combined with 2D WSe2 to develop hybrid QDs/2D‐WSe2 phototransistors for high performance and broadband photodetection are utilized. The device shows a responsivity up to 2 × 105 A W–1, which is orders of magnitude higher than the counterpart of individual material‐based devices. The detection spectra of hybrid devices can be extended to near infrared similar to QDs' response. The high performance of hybrid 0D‐2D phototransistor is ascribed to the synergistic function of photogating effect. PbS QDs can efficiently absorb the input illumination and 2D WSe2 supports a transport expressway for injected photocarriers. The hybrid phototransistors obtain a specific detectivity over 1013 Jones in both ON and OFF state in contrast to the depleted working state (OFF) for other reported QDs/2D phototransistors. The present device construction strategy, photogating enhanced performance, and robust device working conditions contain high potential for future optoelectronic devices.

The binary semiconductor of antimony selenide (Sb 2 Se 3 ) has received wide attention as potential solar cell absorber material recently due to its attractive optoelectronic properties such as proper bandgap (1.17 eV direct and 1.03 eV indirect), large absorption coefficient (>10 5 cm −1 ), decent carrier mobility (≈10 cm 2 V −1 s −1 ), and long carrier lifetime (≈60 ns) as well as its low toxicity, low cost, and earth-abundant constituents. [1] Based on the rapid thermal evaporation (RTE) deposition technology, power conversion efficiencies (PCE) were achieved in superstrate CdS-based Sb 2 Se 3 and Sb 2 (S x ,Se 1−x ) 3 thin film solar cells as 5.6% and 5.79%, [2] respectively. Simultaneously, the substrate Sb 2 Se 3 solar cells with CdS buffer layer were also rapidly developed with PCE over 4% reported by several groups. [3] The traditional CdS buffer layer is toxic to human and environment, and the device reveals low

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sensitivity are the bottlenecks in future commercialization applications. [4,5] Fully-inorganic lead halide perovskites (APbX 3 , A = Cs, Rb, K, etc.), without the organic part affection were expected to resolve the problem of stability. [4,6,7] According to the work of Kubelk et al., fullyinorganic perovskites have similar bandgaps to organo-lead halide analogs and hold much better thermal stability. [4,[7][8][9] Under the scenario of lead-free perovskite, tin (Sn) and germanium (Ge) elements have been considered as hot candidates [10] to replace lead. However, the quick oxidation from Sn 2+ /Ge 2+ to Sn 4+ /Ge 4+ greatly degrades their PCE. [11][12][13] To overcome this problem, heterovalent elements of Sb and Bi were introduced for the implementation of green perovskite. And these perovskite molecular structures transmute from ABX 3 to their derivatives such as A 3 B 2 X 9 .For antimony iodide perovskite (AIP) [14,15] research work, Mitzi and our group combined theoretical calculations, film deposition, and experimental characterizations to understand this new absorber semiconductor. Two kinds of polymorphs exist for Cs 3 Sb 2 I 9 , 0D (dimer) and 2D (layered) phases. Dimer phase exhibits indirect bandgap of 2.50 eV unfavorable for photo voltaics, while layered phase has a direct bandgap of 2.05 eV, a suitable choice as active absorber. The latter one provides similar high level of absorption as CH 3 NH 2 PbI 3 and relatively small in-plane and out-of-plane effective mass. [16][17][18] The layered film could only be synthesized by vapor method with annealing temperature ≈300 °C under the assistance of SbI 3 vapor. [16] Utilizing similar SbI 3 vapor reaction with CsI and SbI 3 precursor film, Chu and co-workers obtained AIP-layered thin film solar cells via a structure of ITO/PEDOT:PSS/AIP/ PC 70 BM/Al and obtained a PCE value of 1.49%. [19] In addition to unique optoelectronic properties, LIP solar cells obtained huge progress highly relying on convenient solution method. The present layered AIP vapor method required high reaction temperature as well as nonuniform composition. Thus, we tried to develop a simple solution method for layered AIP absorbers. According to Zhou and co-workers' theoretical calculations, the AIP dimer phase is an energetically stable Since lead halide perovskite suffers from the obstructions of lead and stability, researchers recently pay more attention to the development of lead-free and stable perovskite absorbers. A typical lead-free antimony iodide perovskite (AIP) is synthesized through vapor reaction at high temperature for photoactive phase. Herein, hydrochloric acid is developed as an intermediate coordinated additive for Cs 3 Sb 2 I 9 photoactive layered phase using HCl-assisted solution method. The uniform and highly crystalline Cs 3 Sb 2 I 9 layered film is obtained by antisolvent engineering. Isopropanol antisolvent is more suitable for present system comparing with traditional lead iodide perovskite-based ones. Physical characterizations manifest the lower trap density, do...