Nanotechnologies / Materials
Image sensor, Color sensor, Smart device

Wavelength-recognizable novel Sb-chalcohalide photodiodeDepartment of Applied Chemistry, Graduate School of Engineering/Innovative Catalysis Science Division
Assistant Professor Ryosuke Nishikubo

https://researchmap.jp/rnishikubo?lang=en

Department of Applied Chemistry, Graduate School of Engineering
Ph.D Student Shaoxian Li				

Department of Applied Chemistry, Graduate School of Engineering/Innovative Catalysis Science Division
Professor Akinori Saeki				https://researchmap.jp/a-saeki?lang=en

Nanotechnologies / Materials

Abstract
Anomalous wavelength-voltage depending property was discovered in originally developed SbSI:Sb2S3-hybrid photovoltaic(PV) device. Although there have various PV materials and devices
been reported, the recognition of both light intensity and wavelength by single PV device have been challenging. We recently
discovered an anomalous wavelength-responsive property in our
originally developed device using antimony-chalcohalide/chalcogenide composite (Fig. 1). Focusing on this behavior, we investigated its detailed property and mechanism.

making thinner device. Thus, WDPE behavior is potentially promising for sensing use. The progress of response speed and device
stability is an important task for practical use.

▍ Background & Results[Background] PV devices are used in various application including solar cells, light sensors, and image sensors. Although PV devices can sense the intensity of light, the sensing of its color had notbeen achieved. Shockley’s equation, which represents the output
property of a PV device, does not contain the wavelength-relatedcomponents. This indicates that output characteristics of a PV device is not affected by irradiated wavelength. However, the author
recently discovered the anomalous wavelength-voltage dependingon nature where short and long wavelength light irradiation provides
lower and higher voltage, respectively. It was denoted as wavelength-dependent photovoltaic effect (WDPE) (Fig. 1). The author
thus investigated the detailed property of WDPE and its mechanism.
[Results] The PV devices (Fig. 1) was fabricated. Then, theoutput characteristics under different wavelength of monochromatic-light was evaluated. In current (J)-voltage (V) measurement, theoutput voltage was linearly changed along with changing the intensity ratio of UV and visible light. The time-dependent photovoltage
measurement revealed that UV irradiation cause significant drop ofvoltage within few seconds, which can be recovered to the initial
voltage after UV is stopped (Fig. 2a).
We also suggested the mechanism (Fig. 2b). Here, high energy
hot-carrier is generated by short-wavelength light. The hot-carrier
can induce the photocatalytic reaction at the surface of active-layer. The reaction provides the chemical species (such as radicalions) which act as trap sites. Thus, the increased surface trap induces the temporal decrease of voltage.
Finally, we successfully demonstrated the dual detection of lightintensity and color. This is the first achievement of the dual detection of light intensity and color by using a single photovoltaic cell.

Fig. 1. Anomalous wavelength-dependent photovoltaic effect.

Fig. 2. a) UV-induced photovoltage drop and recovery. b) The mechanism ofWDPE behavior.

▍ Significance of the research and Future perspective
WDPE is not only fundamentally fascinating, but also provides
a new application. One of the potential applications is the minimization of image sensor (IS) (Fig. 3). Conventional IS detected thedifferent color by using color-filter, where one cell can only detect
one color. To detect the different color by one cell, liquid crystal
color-filter is required which is disadvantageous for minimizing orFig. 3. The example of application for image sensor using dual detection oflight intensity and color.

P a t e n t
Kobayashi, Tai; Nishikubo, Ryosuke; Saeki, Akinori et al. Wavelength-recognizable SbSI:Sb2S3 photovoltaic devices: Elucidation of the mechanism andmodulation of their characteristics. Adv. Funct. Mater. 2023, Accepted. doi: 10.1002/adfm.202311794
Nishikubo, Ryosuke; Li, Shaoxian; Saeki, Akinori. Unprecedented wavelength dependence of an antimony chalcohalide photovoltaic device. Adv. Funct.
Tr e a t i s eMater. 2022, 32, 2201577. doi: 10.1002/adfm.202201577
Nishikubo, Ryosuke; Nazeeruddin, M. K.; Saeki, Akinori et al. Optoelectronic and energy level exploration of bismuth and antimony-based materials forlead-free solar cells chem. Mater. 2020, 32, 6416-6424. doi: 10.1021/acs.chemmater.0c01503
UR
L https://resou.osaka-u.ac.jp/en/research/2022/20220705_2
K e y w o r d photovoltaics, photodetector, sensor