Recently, organic–inorganic halide perovskites have sparked tremendous research interest because of their ground‐breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light‐emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high‐quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three‐dimensional large sized single crystals, two‐dimensional nanoplates, one‐dimensional nanowires, to zero‐dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high‐performance (opto)electronic devices.

A facile in situ solution method was developed for chemical decoration of CH3NH3PbI3 perovskites with reduced graphene oxides (rGOs) to significantly improve the photodetector performance. Such CH3NH3PbI3/rGO molecular hybrids show a 6 times higher ON/OFF ratio and notably faster response speed than neat CH3NH3PbI3.

Highly bendable n-type thermoelectric nanocomposites are successfully developed by embedding metallic Ni nanowires within an insulating poly(vinylidene fluoride) (PVDF) matrix in solution. These nanocomposites exhibit an abnormal decoupling of the electrical conductivity and Seebeck coefficient as a function of Ni contents. A maximum power factor of 220 µW m K and ZT of 0.15 can thus be obtained with 80 wt% Ni at 380 K.

Thermoelectric materials are prepared by developing 3D printing technology. The 3D fabricated Bi0.5 Sb1.5 Te3 samples exhibit amorphous characteristics and thus show an ultralow thermal conductivity of 0.2 W m(-1) K(-1) . 3D printing fabrication readily generates bulk thermoelectric samples of any shape, which is not the case with traditional hot-pressing and spark plasma sintering methods.

Emerging organic–inorganic thermoelectric nanocomposites (TENCs) are promising candidates for the realization of high‐performance flexible thermoelectric generators (TEGs), yet there is an absence of effective means to precisely regulate the film morphology of TENCs. Here, the use of a magnetic field to improve thermoelectric performance of solution fabricated n‐type metallic TENCs is reported. Of particular relevance is that the magnetic field gives rise to aligned Co nanowires (NWs) within a poly(vinylidene fluoride) (PVDF) matrix. Such oriented TENCs exhibit significantly increased electrical conductivity in comparison to identical nanocomposites that are randomly oriented. As a result, the best power factor of oriented Co NWs (80 wt%)/PVDF TENCs reaches 523 µW m−1 K−2 at 320 K, which is among the highest reported n‐type TENCs. By pairing these n‐type TENCs with benchmark p‐type poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) thin films, the fabrication of flexible and planar TEGs that yield a maximum output voltage and power of 26.4 mV and 5.2 µW when ∆T = 50 K, respectively, is reported.