Hybrid organic–inorganic perovskites have shown exceptional semiconducting properties and microstructural versatility for inexpensive, solution‐processable photovoltaic and optoelectronic devices. In this work, an all‐solution‐based technique in ambient environment for highly sensitive and high‐speed flexible photodetectors using high crystal quality perovskite nanowires grown on Kapton substrate is presented. At 10 V, the optimized photodetector exhibits a responsivity as high as 0.62 A W−1, a maximum specific detectivity of 7.3 × 1012 cm Hz1/2 W−1, and a rise time of 227.2 µs. It also shows remarkable photocurrent stability even beyond 5000 bending cycles. Moreover, a deposition of poly(methyl methacrylate) (PMMA) as a protective layer on the perovskite yields significantly better stability under ambient air operation: the PMMA‐protected devices are stable for over 30 days. This work demonstrates a cost‐effective fabrication technique for high‐performance flexible photodetectors and opens opportunities for research advancements in broadband and large‐scale flexible perovskite‐based optoelectronic devices.

Organic hole-transporting materials (HTM) are widely used for high-efficiency solar cells. However, compared with their inorganic counterparts, these materials are often expensive and require complex synthesis methods and the addition of costly dopants to improve their performance. In addition, exposure to the ambient environment affects the chemical stability of some organic materials as well as their device characteristics. Herein, an all-ambient fabrication method is used to develop a CuSCN layer as an alternative to the conventional Spiro-OMeTAD HTM. CuSCN thin films are incorporated into both solar cells and photodetectors to study their effect on the optoelectronic properties of these devices. For the solar cells made with CuSCN, a power conversion efficiency of 14.3% is achieved, with remarkable ambient-stability without encapsulation. Regarding the photodetectors with CuSCN, high-specific detectivity up to 10 12 Jones is exhibited. Solution-processed devices exhibit overall impressive performances and represent an essential step toward large-scale fabrication of efficient, stable, facile, and inexpensive perovskite-based optoelectronic technologies.

Lead sulfide (PbS) quantum dots (QDs) exhibit outstanding size-dependent properties that can be harnessed for optoelectronic applications. For example, they can be used for broadband light detection thanks to their band gap, which can be tuned from the UV to near-infrared. Recent reports show that reducing the dark current in PbS-QDs-based photodetectors leads to improved performance. To this end, we explore the use of low-cost solution-processed p-type copper thiocyanate (CuSCN) films as hole-transporting layer in PbS-QD-based photodetectors. We demonstrate that depositing the CuSCN layer prior to the evaporation of the metal electrode (silver or gold) significantly reduces the dark current, regardless of the electrode material. In turn, the on−off ratio and the detectivity of the fabricated photodiodes have also been improved from 6 to 200 and 10 9 to 10 11 cm Hz 1/2 W −1 , respectively. Moreover, the response time of the photodiodes is preserved when using the CuSCN layer. The thin CuSCN film incorporated between the PbS QD layer and the metal electrode can be engineered to enhance the performance of broadband photodetectors, in a way that is compatible with standard processing approaches.

Epitaxial Bi2FeCrO6 nanoisland arrays with room-temperature multiferroic properties were fabricated by patterned SiO2 template-assisted pulsed laser deposition.

No abstract