Metal halide perovskites (MHPs) are frontrunners among solution-processable materials for lightweight, large-area and flexible optoelectronics. These materials, with the general chemical formula AMX3, are structurally complex, undergoing multiple polymorph transitions...

Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out‐of‐plane orientations of 5,11‐bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band‐dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation‐dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3‐ and 6.2‐times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals.

This tutorial review highlights the role of nanoconfinement in selecting for orientations and polymorphs of organic semiconductor crystals that are optimized for optoelectronic processes, including charge transport and light emission.

Nanoconfining scaffolds can be used to orient and shape organic semiconductor crystals during solution-phase crystallization depending on the scaffold geometry and the native crystal growth habit.

Tri‐cation (Cs+/CH3NH3+/CH(NH2)2+) and dual‐anion (Br–/I–) perovskites are promising light absorbers for inexpensive infrared (IR) photodetectors but degrade under prolonged IR exposure. Here, stable IR photodetectors based on electrospun tri‐cation perovskite fibers infiltrated with hole‐transporting π‐conjugated small molecule 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9‐spirobifluorene (Spiro‐OMeTAD) are demonstrated. These hybrid perovskite photodetectors operate at a low bias of 5 V and exhibit ultra‐high gains with external quantum efficiencies (EQEs) as high as 3009%, decreasing slightly to ≈2770% after 3 months in air. These EQE values are almost ten times larger than those measured for photodetectors comprising bilayer perovskite/Spiro‐OMeTAD films. A high density of charge traps on electrospun fiber surfaces gives rise to a photomultiplication effect in which photogenerated holes can travel through the active layer multiple times before recombining with trapped electrons. Time‐resolved photoluminescence and conductive atomic force microscopy mapping reveal the improved performance of electrospun fibers to originate from the significantly enhanced interfacial surface area between the perovskite and Spiro‐OMeTAD compared to bilayers. As a solution‐based, scalable and continuous method of depositing perovskite layers, electrospinning thus presents a promising strategy for the inexpensive fabrication of high‐performance IR photodetectors for applications ranging from information technology to imaging.

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Abnormal glucose level can cause irreversible damage, including diabetes. In this work, a sensor was designed that mimics the peroxidase property of the natural horseradish peroxidase (HRP). The proposed sensor detects the presence of glucose through the reduction of hydrogen peroxide (H 2 O 2 ) and the oxidation of tetramethylbenzidine (TMB). This sensor shows linear behaviour in the range of 0.001-50 μM with a limit of detection down to 0.8 nM. In addition, a paper-based format of this sensing platform was performed which enables fast and sensitive detection and further reduces the expenses. In this method the linear behaviour of the sensor is between 0.005-40 μM and the detection limit is as low as 2.4 nM. The glucose detection in human saliva was also performed, showing an acceptable accuracy. Thus the sensor is practically suitable for the non-invasive detection of glucose.

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