Citation

Yang Changsheng, Jiang Yuhang, Yu Panpan, Han Shiguo, You Shihai, Zhu Zeng-Kui, Yu Zihao, Luo Junhua. Realizing self-powered broadband photodetection with low detection limit in a trilayered perovskite ferroelectric[J]. Chin. Chem. Lett., 2025, 36(8): 110218  

Changsheng Yang^a,b,1, Yuhang Jiang^a,b,1, Panpan Yu^{b,1, *}, Shiguo Han^c, Shihai You^c, Zeng-Kui Zhu^a,b,c, Zihao Yu^c, Junhua Luo^a,b,c,*     

Photodetectors (PD) which are capable of converting optical signals into electronic signals have a wide range of applications in various fields of the military, optical communication, national economy and so on [1-3]. Particularly, broadband photo response is an important parameter of PD which reflects their capacity to capture a wide range of optical signals from ultraviolet (UV) to near-infrared (NIR) [4-6]. In past decades, metal halide perovskites (MHP) have been considered as the one of most promising materials for photodetectors, ascribed to their intriguing optoelectronic properties, tunable bandgap, as well as large absorption coefficient [7-9]. For instance, MAPbI₃ with the absorption edge of 810 nm exhibit a broadband photodetection ranging from 365 nm to 780 nm [10]. However, the most photodetectors need to apply the external power supply which suffer from the complicated device fabrication and energy consumption. Therefore, there is an urgent need to explore novel semiconductor materials for self-powered photodetectors.

Two-dimensional (2D) perovskite ferroelectrics which strongly couple the ferroelectricity with photoelectric properties sparked increasing interests to explore their potential on optoelectronic fields [11-13]. Especially, the bulk photovoltaic effect (BPVE) induced by spontaneous polarization which can provide the built-in electric field is considered to be an effective strategy for self-powered photodetection [14,15]. For instance, Ji et al. successfully realized self-powered ultraviolet photodetection driving by BPVE based on a 2D perovskite (BPA)₂PbBr₄ (BPA = 3-bromopropylammonium) [16]. Moreover, detection limit which reflects the ability to detect weak lights have busting interests in various field, such as military, day/night surveillance, astronomy, and biomedical imaging [17-19]. For example, the ultraviolet (UV) photodetectors with low detection limit can prevent human from exposure in the illumination of UV lights, because it is evident that UV lights will suppress the human immune system [19-21]. However, the most hybrid perovskite ferroelectrics like (BA)₂CsPb₂Br₇ [22], (BZA)₂CsPb₂Br₇ [23] and EA₄Pb₃Br₁₀ [24] have shortcomings, e.g., poor carrier transport, narrow absorption which strictly limit their further exploration in self-powered photodetection. Therefore, it is very urgent to develop the novel two-dimensional perovskite ferroelectrics with broad absorption for self-powered broadband photodetection.

Herein, the two-dimensional perovskite ferroelectrics (BA)₂EA₂Pb₃I₁₀ (1) with a narrow band gap of 1.86 eV are developed to explore their capability for detecting broadband photons. Due to the synergy of tilted inorganic layers and reorientated organic layers, 1 gives a large spontaneous polarization of 5.6 µC/cm², which generate strong BPVE with an open-circuit voltage of 0.25 V. The broad absorption, photovoltage, as well as promising semiconductor properties endow 1 with excellent self-powered response to photons with broad wavelength (377–637 nm), including high open-off ratio (~10⁵), outstanding responsivity (> 10 mA/W), and promising detectivity (> 10¹¹ Jones), as well as the low detecting limit (~nW/cm²). Our work sheds light on the further exploration of two-dimensional perovskite ferroelectrics towards self-powered broadband photodetection.

The high-quality crystals of 1 grow from an aqueous hydroiodic acid solution containing n-butylamine, ethylamine and Pb(COOH)₂·3H₂O in certain stoichiometric ratios by slowly cooling method (Fig. 1a). The scanning electron microscopy SEM images show no obvious defects, indicating its high quality (Fig. 1b). And the power X-ray diffraction (PXRD) pattern is well accordant with the simulated PXRD pattern (CCDC No. 1912877), verifying its phase purity (Fig. S1 in Supporting information) [25]. As depicted in Fig. 1c, 1 features a unique quantum-well (QW) structure which consist of the infinite [Pb₃I₁₀]_∞ trilayered frameworks as well and organic n-butylamine cations as barriers, providing the great opportunity for higher carrier mobility. Generally, the carrier mobility is enhanced with the increased number of inorganic frameworks, implying the better carrier transporting properties of 1 than other bilayered iodide hybrid perovskites, such as BA₂FAPb₂I₇ [26], (PA)₂(FA)Pb₂I₇ (PA = n-pentylaminium) [27], and BA₂MAPb₂I₇ [28]. Moreover, the reorientation of organic cations and tilt of inorganic layers endow 1 with ferroelectricity, giving a large spontaneous polarization of 5.6 µC/cm² (Fig. 1d). Such large spontaneous polarization can induce the BPVE, providing an effective built-in electric field to drive the carrier separation. The above-room-temperature Curie temperature (313 K), demonstrated by DSC curves (Fig. S2 in Supporting information) guarantee the success of self-powered photodetection at room temperature. As illustrated in Fig. 1e, the onset of absorption is 634 nm and the bandgap is determined to be 1.86 eV by Tauc equation, indicating its capability for capturing photons nearly across the entire visible region. Moreover, 1 exhibits a band-edge emission with the peak at 617 nm, consistent with the absorption bandgap (Fig. S3 in Supporting information). And the bulk resistivity is calculated to be 1.1 × 10¹⁰ Ω cm, allowing the low dark current which is key for detecting the weak light (Fig. S4 in Supporting information).

Figure 1

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Fig. 1. (a) Crystal structure of 1. (b) The picture of crystal. (c) SEM images, (d) P-E hysteresis loops at 298 K. (e) UV–vis diffuse reflectance spectrometry of 1. Inset: calculated bandgap.

Considering the excellent optoelectronic properties of 1, we further investigated its potential on self-powered broadband photodetection by fabricating a two-terminal device. The device diagram is illustrated in Fig. 2a. As depicted in Fig. 2b, 1 exhibit attractive photoresponse to a wide wavelength from 377 nm to 637 nm. And the maximum current is achieved at 520 nm under a same power density of 1.05 mW/cm², in good accordance with the absorption. Herein, it was taken as the representative moonlight to study the photodetection behaviors of 1. Due to the BPVE induced by its spontaneous polarization, 1 exhibits an open-circuit voltage of 0.25 V and a short-circuit current of 89 pA under illumination of 4.15 mW/cm² (Fig. 2c). Additionally, the dark current at 0 V is as low as ~10⁻¹⁴ A, much lower than that of p-n junctions which suggesting superiority of BPVE in self-powered photodetection [29]. Thus, a large on/off ratio of ~10⁴ is achieved under self-powered mode, indicating the prominent self-powered photodetection performance of 1. The symmetric and linear I-V curves imply good ohmic contact between 1 and Ag electrodes, indicating the built-in electric field results from BPVE, not the Schottky barrier (inset of Fig. 2d) [30]. Moreover, the dark current is as low as 53 pA at 10 V, lower than the previously reported compounds, e.g., (1,3-BMACH)(MA)Pb₂I₇ (1,3-BMACH = 1,3-bis(aminomethyl)cyclohexane, I_d = 355 pA) [31], PA₂MAPb₂I₇ (I_d = 100 pA) [32], and (3AMPY)(FA)Pb₂I₇ (3AMPY = 3-(aminomethyl)pyridinium, I_d = 83 pA) [33]. Such a low dark current indicates the low defects and high quality of 1 single crystals, which is favorable for high-performance photodetectors. With the power density increasing to 48 mW/cm², the current rapidly rises to 375 nA. Surprisingly, the photocurrent can be distinguished from dark current even under a weak light with a power density of 97 nW/cm². Moreover, not only for 520 nm light, 1 exhibits an excellent capability to detect weak light for 377, 420 and 637 nm lights (Figs. S5-S7 in Supporting information). Combining with self-powered ability, we believe that 1 is a promising self-powered broadband detecting material for weak lights. Fig. 2e clearly illustrated that 1 exhibits good photoresponse to weak lights at nW/cm² scale under self-powered mode. Specifically, the detection limit is 95, 94, 98 and 96 nW/cm² for 377, 405, 520 and 637 nm, respectively. Those parameters are superior than reported literatures, for example, (FPEA)₂(MA)Pb₂Br₇ (330 nW/cm², 405 nm) [34], MAPbCl₃ (0.6 µW/cm², 375 nm) [35], (FPEA)₂(MA)Pb₂I₇ (100 nW/cm², 520 nm) [36].

Figure 2

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Fig. 2. (a) Schematic diagram of device. (b) Wavelength-dependent photoresponse of 1. (c) I-V curves under dark and illumination of 4.15 mW/cm2. (d) Current-voltage curve under different power density, inset: current-voltage curve under weak light illumination. (e) Self-powered I-t curves under different power density of different wavelength (from top to bottom: 377, 405, 520 and 637 nm).

Responsivity (R) and detectivity (D^*) are another two critical parameters to evaluate the photodetector performance. R and D^* can be determined by the following equation:

where I_photo is the photocurrent, P is the power density of incident light, S is the device area, e is the charge per electron and I_photo is the dark current. The curves of R or D^* versus power density are plotted in Figs. 3a and b, Figs. S9 and S10 (Supporting information). Under different wavelength illumination, R and D^* gradually decreased with the increasing power density of incident light. Specifically, the maximum R is calculated to be 18.8, 42.6, 233.5, and 123.0 mA/W, and D^* is determined to be 2.94 × 10¹¹, 8.74 × 10¹¹, 3.87 × 10¹², and 2.82 × 10¹² Jones for 377, 405, 520, and 637 nm, respectively. Such high R and D^* are superior than those of reported 2D halide perovskites, e.g., (BA)₂(GA)Pb₂I₇ (R = 12.01 mA/W, D^* = 3.3 × 10¹¹ Jones for 520 nm) [37], (1,3-BMACH)(MA)Pb₂I₇ (R = 0.58 mA/W, D^* = 4.82×10¹² Jones for 405 nm) [31], (i-BA)₂(MA)Pb₂I₇ (i-BA = isobutylammonium, R = 12.1 mA/W, D^* = 1.05×10¹¹ Jones for 600 nm) [38]. Notably, 1 can detect weak lights as nW/cm² scale from 377 to 637 nm without external power supply. As depicted in Fig. 3c, 1 shows a fast responding time with the rise time (τ_r) of 248 µs and decay time (τ_d) of 293 µs, faster than reported 2D perovskites, for instance, (Br-BA)₂(EA)₂Pb₃Br₁₀ (τ_r = 289 µs, τ_d = 322 µs) [39], (s-BA)₂(MA)Pb₂I₇ (τ_r = 320 µs, τ_d = 420 µs) [40]. As depicted in Fig. 3d, Furthermore, the light signal remains unchanged after 2 × 10³ on/off cycles, indicating its great stability. Considering all merits discussed above, 1 is a promising material to detect weak broadband light under self-powered mode.

Figure 3

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Fig. 3. (a) R and D* under different powered density. (b) Wavelength-dependent R and D*. (c) Photocurrent responses during on/off illumination switching. (d) Recyclable switching operation of photocurrent response.

In conclusion, we successfully fabricated a self-powered broadband photodetector toward weak lights based on a trilayered iodine perovskite ferroelectric. Due to the synergy of spontaneous polarization and excellent semiconducting properties, 1 exhibits prominent self-powered response to photons with broad wavelength (377–637 nm), including high open-off ratio (~10⁵), outstanding responsivity (> 10 mA/W), and promising detectivity (> 10¹¹ Jones), as well as the low detecting limit (~nW/cm²). This work demonstrate the great potential of 2D perovskite ferroelectric on self-powered broadband photodetectors. 1 exhibits prominent self-powered response to photons with broad wavelength (377–637 nm), including high open-off ratio (~10⁵), outstanding responsivity (> 10 mA/W), and promising detectivity (> 10¹¹ Jones), as well as the low detecting limit (~nW/cm²). This work demonstrate the great potential of 2D perovskite ferroelectric on self-powered broadband photodetectors.

The authors declare no interests.

Changsheng Yang: Writing – original draft, Data curation. Yuhang Jiang: Formal analysis. Panpan Yu: Writing – review & editing, Formal analysis. Shiguo Han: Data curation. Shihai You: Formal analysis. Zeng-Kui Zhu: Formal analysis. Zihao Yu: Formal analysis. Junhua Luo: Supervision, Funding acquisition.

This work was financially supported by the National Natural Science Foundation of China (Nos. 22435005, 22193042, 21921001, 22305105, 52202194, 22201284), Natural Science Foundation of Jiangxi Province (No. 20224BAB213003), the Natural Science Foundation of Fujian Province (No. 2023J05076), Jiangxi Provincial Education Department Science and Technology Research Foundation (No. GJJ2200384).

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2024.110218.