Highly Sensitive Dual‐Band Switchable between Ultraviolet and Visible Region Photomultiplication Type Polymer Photodetectors

Abstract

Dual‐band photomultiplication type polymer photodetectors (PM‐PPDs) are achieved with the structure of ITO/PDIN/poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)benzidine] (poly‐TPD):2,2′‐((2Z,2′Z‐(12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2′′,3′′:4′,5′]thieno‐[2′,3′:4,5] pyrrolo‐[3,2‐g]thieno[2′,3′:4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis‐(methanylylidene)) bis‐(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))‐dimalononitrile (Y6) (100:2, wt/wt)/MoO3/poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) (100:2, wt/wt)/Al. Electron traps can be formed with Y6 surrounded by poly‐TPD or with PC71BM surrounded by P3HT. Trapped electrons near ITO/PDIN or Al electrode can assist hole tunneling injectionunder forward or reverse bias, respectively. The dual‐band PM‐PPDs exhibit ultraviolet spectral response under forward bias dependent on trapped electron distribution near ITO/PDIN electrode, while presenting visible spectral response under reverse bias determined by trapped electron distribution near Al electrode. The performance of dual‐band PM‐PPDs can be optimized by decreasing P3HT:PC71BM layer thickness. The optimal dual‐band PM‐PPDs exhibit external quantum efficiency (EQE) of 2800% at 350 nm under +10 V bias with full‐width at half‐maximum of 80 nm, while achieving EQE of 7500% at 430 nm under −10 V bias. The EQE values of optimal dual‐band PM‐PPDs are markedly improved by raising bias, reaching 13 000% at 350 nm under +16 V bias and 27 000% at 430 nm under −16 V bias. This work provides an effective method to prepare dual‐band PM‐PPDs by manipulating the interfacial trapped electron distribution.

Enhancing Photomultiplication in Organic Photodetectors with Two-Dimensional Metal–Organic Framework Nanosheets

“…This phenomenon may be attributed to the rapid release of electrons from the traps or their recombination with the holes injected from the external circuit. In the PM OPD, the gradual accumulation of photogenerated electrons in traps at the interface results in a slower rise time. , To study the stability of the PM OPD, we measured the photocurrent under continuous illumination for 10,000 s in ambient conditions without encapsulation, as shown in Figure b. We also measured the transient photocurrent of the PM OPD after continuous illumination of 10 4 s, as shown in Figure S7.…”

Dual-Band Photomultiplication-Type Organic Photodetectors with Ultrahigh Signal-to-Noise Ratios

“…32−34 The dual-band PM-type OPDs exhibit two distinct spectral response ranges, which can be well explained according to the working mechanism of PM-type OPDs, expressed as interfacial trap-assisted charge tunneling injection from an external circuit. 35,36 The energy levels of the used materials and normalized absorption spectra of pure films are displayed in Figure 1c,d. Under forward bias, the spectral response range of dual-band PM-type OPDs is determined by the trapped electrons distributed in PC 71 BM near the PNDIT-F3N/ITO side.…”

“…A wide-bandgap PNDIT-F3N material is used as an anode interfacial layer to enhance the hole injection barrier from indium tin oxide (ITO) into the active layer, leading to the J D being as low as possible and the PM phenomenon under forward bias. The PNDIT-F3N interfacial layers are commonly used as the cathode interfacial layer in preparing highly efficient organic solar cells. − The dual-band PM-type OPDs exhibit two distinct spectral response ranges, which can be well explained according to the working mechanism of PM-type OPDs, expressed as interfacial trap-assisted charge tunneling injection from an external circuit. , The energy levels of the used materials and normalized absorption spectra of pure films are displayed in Figure c,d. Under forward bias, the spectral response range of dual-band PM-type OPDs is determined by the trapped electrons distributed in PC 71 BM near the PNDIT-F3N/ITO side.…”

Epitaxy growth of MAPbBrxCl3−x single-crystalline perovskite films toward spectral selective detection in both broadband and narrowband ranges

“…23,50,51 Photodetectors in general can work exclusively either in the broadband or in the narrowband; however, multifunctional photodetectors can respond to photons in both broadband and narrowband ranges and are expected to introduce a new level of versatility to optoelectronics. 52–55…”

“…23,50,51 Photodetectors in general can work exclusively either in the broadband or in the narrowband; however, multifunctional photodetectors can respond to photons in both broadband and narrowband ranges and are expected to introduce a new level of versatility to optoelectronics. [52][53][54][55] In this study, we successfully grew mixed-halide singlecrystalline perovskites (MAPbBr x Cl 3Àx , where x = 0-3) on a MAPbCl 3 crystal substrate through a facile liquid-phase epitaxial (LPE) method, the thickness of the expected epilayer can be controlled from tens of micrometers to hundreds of micrometers in several hours. Through experimental characterization, we demonstrated the ability to control the composition and tune the bandgap (2.19-2.91 eV) across the full range from x = 0 to 3.…”