Fig. 1. (a), (b) Schematic crystal structure of representative perovskite materials ${\mathrm{CH}}_3{\mathrm{NH}}_3{\mathrm{PbI}}_3$ and ${\mathrm{CsPbBr}}_3$, simulated from Vesta.3 Software; (c) comparative optical absorption behavior of semiconducting materials. Reproduced from Ref. [6] with permission. Copyright 2014, Springer Nature.

Fig. 2. Schematic diagrams of working principle of SPPDs in PV mode: heterojunction type (left side) and Schottky type (right side).

Fig. 3. (a) Preparation process of the ${\mathrm{MAPbBr}}_3/{\mathrm{MAPbI}}_x{\mathrm{Br}}_{3-x}$ heterojunction; (b) responsivity of ${\mathrm{APbBr}}_3/{\mathrm{MAPbI}}_x{\mathrm{Br}}_{3-x}$ and single crystal ${\mathrm{MAPbBr}}_3$ PDs at zero bias under the incident light with wavelengths of 350–800 nm and 400–800 nm, respectively; (c) schematic energy level diagram at the ${\mathrm{MAPbBr}}_3/{\mathrm{MAPbIxBr}}_{3-x}$ junction under irradiation. Reproduced with permission from Ref. [56]. Copyright 2016, American Institute of Physics. (d) Photographic image of the as-grown heterostructure single crystal (top); SEM image of the heterostructure interface (bottom). (e) Band diagram of the $(4\text{-AMP}){(\mathrm{MA})}_2{\mathrm{Pb}}_3{\mathrm{Br}}_{10}/{\mathrm{MAPbBr}}_3$ heterostructure detector; (f) plots of the $R$ and $D^{*}$ as a function of light intensity; (g) response speed of $(4\text{-AMP}){(\mathrm{MA})}_2{\mathrm{Pb}}_3{\mathrm{Br}}_{10}/{\mathrm{MAPbBr}}_3$ heterostructure device at rise edges and fall edges. Reproduced with permission from Ref. [57]. Copyright 2020, Wiley-VCH. (h) Schematic illustration of the Au–Al electrodes separated by 30 μm on ${\mathrm{MAPbI}}_3$ single crystal; (i) schematic illustration of the working mechanism for Schottky junction based on asymmetric electrodes; (j) photocurrent response of $\mathrm{Au}/{\mathrm{MAPbI}}_3/\mathrm{Al}$ device at different wavelengths; (k) spectral photoresponsivity of ${\mathrm{MAPbI}}_3$ single crystal PD. Reproduced with permission from Ref. [58]. Copyright 2016, Royal Society of Chemistry.

Fig. 4. (a) Photographic image of ${\mathrm{CsPbBr}}_3$ single crystal; (b) I-V curve of device $\mathrm{Au}/{\mathrm{CsPbBr}}_3/\mathrm{Pt}$ in dark and under illumination; (c) photoresponse of device $\mathrm{Au}/{\mathrm{CsPbBr}}_3/\mathrm{Pt}$ under light pulses measured under zero bias. Reproduced with permission from Ref. [28]. Copyright 2017, Wiley-VCH. (d) Carrier separation transmission diagram of the device based on ${\mathrm{CH}}_3{\mathrm{NH}}_3{\mathrm{PbI}}_3$ single crystal PD; (e) variation of light responsivity of devices with different channel widths; (f) dependence of responsivity and on–off ratio on the light intensity. Reproduced with permission from Ref. [60]. Copyright 2021, Elsevier.

Fig. 5. (a) Schematic illustration of ${\mathrm{MAPbI}}_3$ NC synthesis; (b) TEM image of ${\mathrm{MAPbI}}_3$ NCs (the inset shows ${\mathrm{MAPbI}}_3$ nanocrystal size distribution plot); (c) schematic diagram of the ${\mathrm{MAPbI}}_3$ NC based self-powered PD; (d) J-V curves of the ${\mathrm{MAPbI}}_3$ NC-based self-powered PD under 808 nm illumination; (e) photocurrent versus time for the PD under light on/off cycles at 0 V under 808 nm illumination. Reproduced with permission from Ref. [50]. Copyright 2020, Wiley-VCH. (f) Cross-sectional SEM image of ITO/ZnO(70 nm)/CdS(150 nm) /${\mathrm{CsPbBr}}_3(200\mathrm{nm})/\mathrm{Au}$ trilayer PDs; (g) I-V curve of trilayer PD device in dark and under $85\mathrm{\mu W}{\mathrm{cm}}^{-2}$ 405 nm illumination; (h) potential charges generation and transportation process under $85\mathrm{\mu W}{\mathrm{cm}}^{-2}$ 405 nm illumination illustrated by band diagram. Reproduced with permission from Ref. [67]. Copyright 2020, Institute of Physics.

Fig. 6. (a) Schematic illustration of the synthesis process of the ${\mathrm{CsPbBr}}_3$ NWs and ${\mathrm{CsPbBr}}_3$ micro- and nanostructures; (b) schematic illustration of the perovskite NW PD; (c) energy band diagram of the perovskite NW PD. (d) J-t curve at the light intensity of $6.4\times {10}^{-4}\mathrm{mW}{\mathrm{cm}}^{-2}$; (e) responsivity and detectivity of the device under various optical power. Reproduced with permission from Ref. [68]. Copyright 2018, Elsevier. (f) Schematic illustration of the fabrication process of the P3PCS PD; (g) ${\mathrm{CsPbBr}}_3$ nanowire array; (h) schematic of device structure; (i) responsivity and detectivity curves of P3PCS device; (j) long-term photoresponse curves of P3PCS device under $100\mathrm{mW}{\mathrm{cm}}^{-2}$ white light at 0 V. Reproduced with permission from Ref. [69]. Copyright 2019, Wiley-VCH.

Fig. 7. (a) SEM image of ${\mathrm{CsPbBr}}_3$ microplatelets shows sharp edge and smooth surface morphology. (b) Schematic layout of the perovskite ${\mathrm{CsPbBr}}_3$ microplatelets PD based on vertical Schottky junction structure; (c) I-V characteristics of the ${\mathrm{CsPbBr}}_3$ microplatelets PD under 405 nm light illumination with different density; (d) normalized I-t curves of ${\mathrm{CsPbBr}}_3$ microplatelets PD with long-term storage without encapsulation. Reproduced with permission from Ref. [75]. Copyright 2020, Royal Society of Chemistry. (e) Schematic of fabricating process of the ${\mathrm{CsPbBr}}_3$ microcrystal-based PD; (f) room temperature spectral responsivity curves of the ${\mathrm{CsPbBr}}_3$ microcrystal-based PD at 0 V bias. Reproduced with permission from Ref. [76]. Copyright 2019, American Chemical Society. (g) SEM image of ${\mathrm{CsPbBr}}_3$ microcrystal perovskite film. The inset is a digital photograph of the perovskite film under 365 nm purple flashlight. (h) Schematic illustration of the ${\mathrm{CsPbBr}}_3$ microcrystal perovskite PD; (i) power-dependent $R$ and $D^{*}$ ${\mathrm{CsPbBr}}_3$ microcrystal perovskite PD under 0 V bias. Reproduced with permission from Ref. [77]. Copyright 2019, American Chemical Society.

Fig. 8. (a) Device structure of the hybrid perovskite PD; (b) LDR of the PD with the device structure $\mathrm{ITO}/\mathrm{PEDOT}:\mathrm{PSS}/{\mathrm{CH}}_3{\mathrm{NH}}_3{\mathrm{PbI}}_{3-x}{\mathrm{Cl}}_x/\mathrm{PCBM}/\mathrm{PFN}/\mathrm{Al}$. The PD has a large LDR of 4100 dB. Reproduced with permission from Ref. [85]. Copyright 2014, Springer Nature. (c) SEM image of ${\mathrm{MAPbI}}_{3-x}{\mathrm{Cl}}_x$ thin films on glass substrate; (d) schematic representation of a photodetector device configuration; (e) transient photocurrent properties of device under illumination at 632 nm; (f) long-term photo stability illuminated under $1000\mathrm{\mu W}/{\mathrm{cm}}^2$ with different intervals up to 500 h. Reproduced with permission from Ref. [86]. Copyright 2020, Elsevier. (g) SEM image of PMMA-modified ${\mathrm{CsPbBr}}_3$ film; (h) schematic and cross-sectional SEM image of the as-fabricated PD with a structure of $\mathrm{ITO}/{\mathrm{CsPbBr}}_3/\mathrm{PMMA}/\mathrm{Ag}$. Reproduced with permission from Ref. [87]. Copyright 2020, Royal Society of Chemistry. (i) Schematic structure of PD based on all-inorganic perovskite ${\mathrm{CsPbI}}_x{\mathrm{Br}}_{3-x}$; (j) current density-voltage (J-V) curves of ${\mathrm{CsPbIBr}}_2$-based PDs under dark and illumination of 450 nm monochrome light with intensity of $1\mathrm{\mu m}{\mathrm{cm}}^{-2}$ to $1\mathrm{mW}{\mathrm{cm}}^{-2}$; (k) photoresponsivity evolution of PDs based on inorganic perovskite ${\mathrm{CsPbI}}_x{\mathrm{Br}}_{3-x}$ and hybrid perovskite ${\mathrm{MAPbI}}_3$ in air ambient condition without encapsulation. Reproduced with permission from Ref. [88]. Copyright 2018, Wiley-VCH. (l) Schematic illustration of as-fabricated self-powered PD based on ${\mathrm{Cs}}_x{\mathrm{DMA}}_{1-x}{\mathrm{PbI}}_3$ perovskite films; (m) responsivity spectrum of the self-powered PD based on the film with $\mathrm{CsI}/{\mathrm{DMAPbI}}_3$ molar ratio of $1:2$ in the precursor at 0 V; (n) variation of spectral responsivity with time of the self-powered PD in air (10%–20% RH) at a bias voltage of 0 V under 532 nm illumination. Reproduced with permission from Ref. [89]. Copyright 2020, Elsevier. (o) Disordered state of ions under dark (upper) and mobile ions accumulated at the opposite interfaces under illumination due to the light-induced self-poling effect (lower), resulting in the built-in electric field; (p) energy band schematics of the MOS structure under dark before contact. Reproduced with permission from Ref. [90]. Copyright 2019, Royal Society of Chemistry.

Fig. 9. (a) Device structure of self-powered PD with ${\mathrm{MAPbI}}_3$ as the photosensitive and triboelectric layer; (b) change of ${\mathit{V}}_{\mathrm{oc}}$ upon repeated illumination that varies in intensity at $100\mathrm{mW}{\mathrm{cm}}^{-2}$. Reproduced with permission from Ref. [93]. Copyright 2015, American Chemical Society. (c) Schematic of a triboelectric-assisted perovskite PD showing charge carrier separation assisted by the triboelectric charges created by the TENG; (d) schematic diagram and the working principle of the (+) triboelectric-assisted perovskite PD; (e) transient photoresponse of the triboelectric-actuated perovskite PD (blue) and perovskite PD without assistance of triboelectricity (red) under alternating on–off laser light (50 mW) illumination with a 3 Hz chopping frequency. Reproduced with permission from Ref. [94]. Copyright 2019, Elsevier.

Fig. 10. (a) Plane-view SEM image of ${\mathrm{CsPbBr}}_3$ perovskite thin films ${\mathrm{Al}}_2{\mathrm{O}}_3$-modified FTO substrates; (b) photoresponse curves of ${\mathrm{CsPbBr}}_3$ perovskite PDs, ${\mathrm{Al}}_2{\mathrm{O}}_3/{\mathrm{CsPbBr}}_3$ perovskite PDs, and ${\mathrm{Al}}_2{\mathrm{O}}_3/{\mathrm{CsPbBr}}_3/{\mathrm{TiO}}_2$ perovskite PDs, respectively; (c) energy band diagram of heterojunctions; (d) current–voltage (I-V) curves of PDs under dark and illumination of 405 nm laser with intensity of $6.2\mathrm{\mu W}{\mathrm{cm}}^{-2}$ to $114\mathrm{mW}{\mathrm{cm}}^{-2}$; (e) photoresponse curves of ACT PDs under modulated 405 nm laser with various light intensity (0 V); (f) light current and dark current stability at different days for hard substrate device; (g) light current and dark current of flexible device after different bending cycles. Reproduced with permission from Ref. [123]. Copyright 2019, Wiley-VCH.

Fig. 11. (a) FESEM image of a typical PD with Au/Ag electrode pair; (b) I-V curves of the CH₃NH₃PbI₃ MWs array-based PDs with asymmetric contact electrodes (Au/Ag, Au/Al); (c) histogram of ${\mathit{V}}_{\mathrm{o}\mathrm{c}}$ and $I_{\mathrm{s}\mathrm{c}}$ for devices with different asymmetric electrode pairs; (d) dark current and photocurrent of the flexible PD being bent to various radii. Reproduced with permission from Ref. [71]. Copyright 2019, Wiley-VCH. (e) Device structure and (f) cross-sectional SEM image of ${\mathrm{MAPbI}}_3:\text{graphene}$ QD based PD. (g) NEP/spectral detectivity of PD. The inset shows excellent flexibility of the PD. (h) Evolution of responsivity during repeated 1000 bending cycles at $\lambda =600\mathrm{nm}$ and $d=4\mathrm{mm}$. Reproduced with permission from Ref. [124]. Copyright 2019, American Chemical Society.

Fig. 12. (a) Schematic illustration of ferroelectric polarization-induced formation of internal electric field in the nanowire array device; (b) schematic illustration of the fabrication process of flexible P(VDF-TrFE)/perovskite hybrid nanowire arrays-based PD; (c) 650 nm wavelength light illumination of flexible P(VDF-TrFE)/perovskite PDs with various power intensities at 0 V; (d) I-t curves of the poled perovskite-0.6 device under 650 nm light illumination at bending angles with the intersection angle between bending direction and nanowire direction of 0°. Reproduced with permission from Ref. [125]. Copyright 2019, Wiley-VCH. (e) I-t curve of flexible P(VDF-TrFE)/perovskite PDs at different bending cycles. Reproduced with permission from Ref. [126]. Copyright 2019, Wiley-VCH.

Fig. 13. (a) Schematic diagram of the SFPDs with integrated TENG; (b) change in the measured voltage ($\mathrm{\Delta }V$) and voltage responsivity of the device at different light intensities; (c) $\mathrm{\Delta }V$ at various angles of incident light. Reproduced with permission from Ref. [129]. Copyright 2018, Wiley-VCH. (d) Schematic illustration of the integrated nanosystem, consisting of an energy conversion unit, a light sensing unit, and a current measurement system. (e) J-V curves of the as-fabricated integrated perovskite solar cell; (f) photoresponse curves after 100 and 200 bending cycles. Reproduced with permission from Ref. [130]. Copyright 2016, Wiley-VCH.

Fig. 14. (a) Photoresponsivity evolution of PDs based on inorganic perovskite ${\mathrm{CsPbI}}_x{\mathrm{Br}}_{3-x}$ and hybrid perovskite ${\mathrm{MAPbI}}_3$ at 100°C in ${\mathrm{N}}_2$ ambient condition. XRD spectra and digital photographs of (b) ${\mathrm{CsPbIBr}}_2$ and (c) ${\mathrm{MAPbI}}_3$ devices before and after heated at 100°C in ${\mathrm{N}}_2$-filled glove box for 244 h. The obvious ${\mathrm{PbI}}_2$ peak in XRD spectrum of ${\mathrm{MAPbI}}_3$ devices after being heated indicates the decomposition of ${\mathrm{MAPbI}}_3$. Reproduced with permission from Ref. [88]. Copyright 2018, Wiley-VCH. (d) Thermal stability of ${\mathrm{MAPbI}}_3$ NCs; photographic image of samples under 365 nm illumination. The samples are annealed at 40°C, 50°C, 60°C, 70°C, and 80°C for 10 min in open air. Reproduced with permission from Ref. [50]. Copyright 2020, Wiley-VCH.