A novel approach for designing efficient broadband photodetectors expanding from deep ultraviolet to near infrared

Ding et al. Light: Science & Applications (2022)11:91 https://doi.org/10.1038/s41377-022-00777-w ARTICLE Official journal of the CIOMP 2047-7538 www.nature.com/lsa Open Access A novel approach for designing efficient broadband photodetectors expanding from deep ultraviolet to near infrared 1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; Nan Ding1, Yanjie Wu1, Wen Xu1,2 ✉, Jiekai Lyu1, Yue Wang1, Lu Zi1, Long Shao1, Rui Sun1, Nan Wang1, Sen Liu1, Donglei Zhou1, Xue Bai1, Ji Zhou3 and Hongwei Song1 ✉ Abstract Broadband photodetection (PD) covering the deep ultraviolet to near-infrared (200–1000 nm) range is significant and desirable for various optoelectronic designs. Herein, we employ ultraviolet (UV) luminescent concentrators (LC), iodinebased perovskite quantum dots (PQDs), and organic bulk heterojunction (BHJ) as the UV, visible, and near-infrared (NIR) photosensitive layers, respectively, to construct a broadband heterojunction PD. Firstly, experimental and theoretical results reveal that optoelectronic properties and stability of CsPbI3 PQDs are significantly improved through Er3+ doping, owing to the reduced defect density, improved charge mobility, increased formation energy, tolerance factor, etc. The narrow bandgap of CsPbI3:Er3+ PQDs serves as a visible photosensitive layer of PD. Secondly, considering the matchable energy bandgap, the BHJ (BTP-4Cl: PBDB-TF) is selected as to NIR absorption layer to fabricate the hybrid structure with CsPbI3:Er3+ PQDs. Thirdly, UV LC converts the UV light (200–400 nm) to visible light (400–700 nm), which is further absorbed by CsPbI3:Er3+ PQDs. In contrast with other perovskites PDs and commercial Si PDs, our PD presents a relatively wide response range and high detectivity especially in UV and NIR regions (two orders of magnitude increase that of commercial Si PDs). Furthermore, the PD also demonstrates significantly enhanced air- and UV- stability, and the photocurrent of the device maintains 81.5% of the original one after 5000 cycles. This work highlights a new attempt for designing broadband PDs, which has application potential in optoelectronic devices. Introduction Photodetectors (PDs) are the technical functional components for capturing and converting ultraviolet (UV) to near-infrared (NIR) photons into electronic outputs1–5. The broadband optical detection ability, especially from UV to NIR range, is critical for applications including medical monitoring, video imaging, optical communication, and civil engineering6–12. Generally, the commercial Correspondence: Wen Xu () or Hongwei Song () 1 State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China 2 Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, Dalian Minzu University, Dalian 116600, China Full list of author information is available at the end of the article These authors contributed equally: Nan Ding, Yanjie Wu silicon PDs present the relatively broad wavelength response range from 400–1100 nm13,14, but usually suffer from high cost and low detectivity, especially in the UV region. Solution-processable broadband PDs based on soluble materials have numerous advantages of low cost, simple preparation, and high sensitivity, which has become the next generation of new detectors15–17. Encouragingly, solution-processable metal halide perovskites process outstanding characteristics of large absorption coefficient, long diffusion length, low trapping density, and high photoluminescent quantum efficiency (PLQY), which have shown unprecedented radical progress for various optoelectronic devices, including solar cells (SCs), light-emitting diodes (LEDs), and photodetectors (PDs)11,18,19. Among them, all-inorganic © The Author(s) 2022 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Ding et al. Light: Science & Applications (2022)11:91 perovskite quantum dots (ABX3, A = Cs; B = Pb, Ge, Sn; X = Cl, Br, I) (PQDs) have attracted extensive interest in broadband PDs, owing to their wide-range tunability of bandgap, large absorption cross-section, high carrier mobility, etc18,20–23. Especially, CsPbI3 PQDs process narrow bandgap of 1.73 eV, becoming a candidate for broadband PDs24. For example, Tian et al. fabricated 2-aminoethanethiol (AET)/CsPbI3 PQDs compositebased PDs device, exhibiting a high responsivity of 105 mA W−1 and the detection wavelength covering the visible light22. However, its spectrum covers mainly the blue to visible light range (400–700 nm), short of UV response and NIR absorption, due to the insensitivity to UV light and limitation of the bandgap. In addition, they also encounter relatively high trap density, poor carrier mobility, and high susceptibility to moisture and UV light, generating phase transition from cubic to orthorhombic phase25–27. The above issues severely limit its photodetection of broadband response spectrum with high stability and responsivity. To overcome the challenges mentioned above, much efforts have been made to improve the stability and responsivity, and to expand the spectral response range of perovskite-based PDs. A number of metal ions (eg., Zn2+, Cr3+, Nd3+, Er3+, Ce3+) doping have been proved to be a promising way to boost the optical and electrical performance of perovskite materials28–31, including the decrease of trap density and the improvements of carrier mobility, stability, and photoluminescence quantum yield (PLQY). Meanwhile, the strategy of integrating perovskite with NIR absorption materials (e.g., organic bulk heterojunction (BHJ), lead sulfide quantum dots, etc.) was attempted to expand the spectral response range of PDs to the NIR region32–34. For example, Chen et al. achieved broadband photodetectors with high NIR external quantum efficiency of over 70% in organic-inorganic perovskite/BHJ hybrid35. Nevertheless, such PD has low responsivity in the UV region and relatively poor stability of organic-inorganic perovskite. The scheme of luminescent conversion was proven to be an effective route to enlarge the response to the UV by absorbing and converting UV to visible photon (...truncated)