Search

The perovskite single crystals (PSC) produced by solution‐processed metallic ions doping have a thick p–n junction (greater than 10 µm). Meanwhile, to achieve high responsivity, the carrier drift length (µτE) has to be larger than the dimensions of the detector. If the p–n junction is quite thick, a high bias voltage is required. For the practical application of photodiode, it is imperative to find a means to generate a thin p–n junction. A productive technique is suggested for forming a thin p–n junction by diffusing metallic ions, resulting in a longer drift length of the carrier than the depletion width. Thinner p–n junction leads to reduced dark current density (0.5 µA cm−2), low trap density (5.71 × 108 cm−3), high mobility (417 cm2 V−1 s−1), and hence increased responsivity (77.69 A W−1) for 30 µW cm−2 UV illumination under a low applied voltage of −15 V. A quick response time with a rise/fall duration of 22 ms/30 ms under 0 V and long‐term stability for over 3 months in ambient airis achieved. To comprehend the performance with the thinner p–n junction‐based photodiodes, the results under UV–Vis illumination are examined and compared. The outcomes hint at a method that holds promise for producing efficient photodiodes. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (PSCs) photodiodes with p–n junctions have been widely studied due to their effective blocking of injected current with barriers and quickly separating the electrons and hole pairs with a built-in electric field. Here, we report a solution-processed epitaxial (SPE) growth method to fabricate p–n photodiodes based on MAPbBr3 PSCs. In the structure of the MAPbBr3 PSCs, bismuth donor doping will change the conduction type from p-type to n-type and redshift the absorption edge along with the increase in Bi concentration. Therefore, this work successfully fabricates the p–n photodiodes with homo-epitaxial Bi-doped (n-type) MAPbBr3 layers grown on the surface of undoped (p-type) MAPbBr3 PSCs substrates through the SPE growth method. The p–n photodiodes achieve a tunable spectral response by simply adjusting the Bi doping concentrations of homo-epitaxial MAPbBr3 layers. The spectral response peaks redshift from 559 to 601 nm, with an increasing Bi doping level of 0% to 15%. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (PSCs) can be used to fabricate high performance photoelectric detectors due to their superior optoelectronic characteristics. Generally, an external electric field needs to be applied in PSC-based detectors to improve their charge collection efficiency. However, the large external electric field increases the dark current, which will enlarge the noise current. To alleviate this drawback, an approach of fabricating a PSC-based heterojunction is proposed in this work, which contributes to reduced dark current in a relatively high reverse electric field. In this study, a heterojunction formed by epitaxially growing MAPbBr3 PSCs on Bi3+-doped MAPbCl3 PSCs is reported, and it shows relatively low trap density and higher built-in potential. The as-fabricated Au-MAPbBr3/Bi3+-doped MAPbCl3 PSC heterojunction-Au photodiode shows smaller dark current density, better long-term current stability and reduced noise level by approximately four orders compared to the Au–MAPbBr3 PSCs–Au photoconductor device under an external reverse voltage of 100 V (mean electric field of ∼31.5 V mm−1). Moreover, the pN heterojunction photodiode shows favorable X-ray detection performance, with a fast response time of 4.89 μs and high sensitivity of 1.72 × 103 μC Gyair−1 cm−2 for 50 kVp X-ray photons under a reverse electric field of 31.5 V mm−1. This work confirms that the epitaxial fabrication of PSC heterojunctions may be a promising strategy to enhance the performance of X-ray photodetectors. [ABSTRACT FROM AUTHOR]