Designing absorber-transporter combination for hybrid photodetector and photothermoelectric energy conversion

Surojit Chattopadhyay^1*

¹Institute of Biophotonics, National Yang Ming Chiao Tung University, Taipei, Taiwan

* Presenter:Surojit Chattopadhyay, email:sur@nycu.edu.tw

Abstract: We demonstrate high responsivity broadband photodetectors using various photoabsorbers, such as perovskites, borophene, and upconversion materials, dispersed on two dimensional charge transporters, such as graphene and MoS2. We also design dark composites of perovskite and MoS2 for photothermoelectric conversion using a thermoelectric generator module for possible small power applications such as Li-ion battery charging.

We demonstrate the design rationale for photoelectric (PE) and photothermal (PT) conversion in semiconductor and inorganic absorbers for next-generation photodetectors (PDs) and photothermoelectric (PTE) power generation. The high-speed commercial semiconductor p-n junction-based PDs lack responsivity. To address this issue, we propose the use of separate absorbers and 2-dimensional (2D) high mobility charge transporters such as Graphene/MoS2/ borophene. Absorbers, such as upconversion nanoparticles (UCNPs), perovskites, bismuth telluride (Bi2Te3), and dual-functional 2D materials like MoS2 and borophene, are used. The use of photoconductors, instead of conventional junctions, increases the responsivity to unprecedented values. However, the complicated interfaces slow down the charge transport and limit the speed of these PDs. Additionally, the use of the photoconductors also requires proper use of substrates, without which the device suffers. The PD device made with the same absorber responds differently when SiO2/Si, quartz, or PDMS polymer substrates are used. First, we demonstrate broadband perovskite PDs, with graphene transporters, with responsivity values exceeding 106 A/W. We show strategies, such as the incorporation of superhalides (PF6), to impart environmental stability to the degradation-prone material [1,2]. Next, we show how the use of UCNPs on graphene and MoS2 can increase the usable spectrum of light into the infrared [3]. We also probe the possibility of using borophene PD (Fig. 1a) and its performance (Fig. 1b) after the introduction of a graphene charge transporter layer (Fig. 1c, d), highlighting the role of graphene in enhancing both photocurrent and response speed [4].
On the PTE energy conversion designs, we demonstrate the use of a dark double perovskite-MoS2 composite as a PT coating on a commercial thermoelectric generator (TEG) module that can charge a mobile phone battery within 5 minutes using a simple desktop lamp illumination [5]. The optimal double perovskite (CCSC)-MoS2 composite demonstrated a maximum temperature gradient of ~30 °C, and PTE voltage output of 500 mV, on a TE generator corresponding to a maximum power density of 3.26 mW cm-2 under a 3000 K lamp at 450 mW cm-2.
In summary, we demonstrate novel material designs as super-absorbers for PE and PT conversion that have real applications in PDs, and power generation. We demonstrate the extension of the spectral usability of light in composite materials. We propose the use of a separate photoabsorber, and charge transporter as a strategy for high responsivity. We demonstrate the critical role of the substrate for these hybrid photodetectors. We show the use of a perovskite-MoS2 composite for photothermoelectric power generation for Li-ion battery charging using a common desktop lamp.

References

[1] Mega Broadband Photoresponsivity in Degradation-Controlled Super-Halide PF6 substituted Perovskite@graphene Hybrid Photodetectors. Varun Sridhar, Mohammad Rameez, Pushpa Selvarasu, Digvijay Singh Tomar, Sapthami Hegde, Ruei San Chen, Chien Ting Wu, Chen Hsiung Hung, Surojit Chattopadhyay*; Mater. Today Phys. 40, 101294 (2024).
[2] Gradient Dion-Jacobson Phase Stable Quasi-2D Perovskite@Graphene Hybrid for High Responsivity Photodetectors. Sapthami Hegde, Varun Sridhar, Ruei San Chen, Surojit Chattopadhyay*; Advanced Optical Materials 12, 2400232 (2024).
[3]Ultrasensitive broadband photodetector using electrostatically conjugated MoS2-upconversion nanoparticle nanocomposite; Sandip Ghosh, Wen Cheng Chiang, Muhammad Yusuf Fakhri, Chien Ting Wu, Ruei San Chen, and Surojit Chattopadhyay*, Nano Energy 67, 104258 (2020).
[4]Photogating enhanced photodetection in substrate-assisted borophene-graphene hybrids”, by Digvijay Singh Tomar, Ruei San Chen, and Surojit Chattopadhyay*, Nanoscale 17, 19363 (2025).
[5] Harnessing photothermal synergy of Cs4CuSb2Cl12/MoS2 composite for photothermoelectric energy harvesting and small power application, Varun Sridhar, Chien-Ting Wu, and Surojit Chattopadhyay*, ACS Applied Materials and Interfaces 17, 39584 (2025).

Keywords: Photodetectors, Hybrid, Photothermoelectric, Perovskite, 2D materials