1
|
Asahi S, Kaizu T, Kita T. Adiabatic two-step photoexcitation effects in intermediate-band solar cells with quantum dot-in-well structure. Sci Rep 2019; 9:7859. [PMID: 31133644 PMCID: PMC6536537 DOI: 10.1038/s41598-019-44335-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 05/15/2019] [Indexed: 11/26/2022] Open
Abstract
We studied the dynamics of electrons generated by two-step photoexcitation in an intermediate-band solar cell (IBSC) comprising InAs/GaAs/Al0.3Ga0.7As dot-in-well (DWELL) structure using time-resolved photocurrent (TRPC) measurement. The examined IBSC exhibited considerably slower photocurrent decay than a conventional InAs/GaAs quantum dot IBSC, which is due to the extraordinarily long-lived electrons in the DWELL. In order to retrieve the electron lifetime from the decay profile, we developed a model reproducing the observed decay and performed parameter fitting. The fitting results indicate that the electron lifetime in the DWELL is approximately 30 μs. In the two-colour excitation TRPC measurement, we found that an additional infrared (IR) light accelerates the photocurrent decay while the photocurrent increases by approximately 3%, because the additional IR light causes two-step photoexcitation of electrons in the DWELLs towards the conduction band. Furthermore, we demonstrated that the open-circuit voltage increases with increasing of the contribution of the second IR excitation process.
Collapse
Affiliation(s)
- Shigeo Asahi
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan.
| | - Toshiyuki Kaizu
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Takashi Kita
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| |
Collapse
|
2
|
Abstract
GaN-based materials are widely used for light emission devices, but the intrinsic property of wide bandgap makes it improper for photovoltaic applications. Recently, manganese was doped into GaN for absorption of visible light, and the conversion efficiency of GaN-based solar cells has been greatly improved. We conducted transient optical measurements to study the carrier dynamics of Mn-doped GaN. The lifetime of carriers in the Mn-related intermediate bands (at 1.5 eV above the valence band edge) is around 1.7 ns. The carrier relaxation within the Mn-induced bandtail states was on the order of a few hundred picoseconds. The relaxation times of different states are important parameters for optimization of conversion efficiency for intermediate-band solar cells.
Collapse
|
3
|
Yan C, Zhao H, Perepichka DF, Rosei F. Lanthanide Ion Doped Upconverting Nanoparticles: Synthesis, Structure and Properties. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:3888-3907. [PMID: 27345736 DOI: 10.1002/smll.201601565] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Indexed: 06/06/2023]
Abstract
Lanthanide doped upconverting nanoparticles (UCNPs) have emerged as a new class of luminescent materials, with major discoveries and overall significant progress during the last decade. Unlike multiphoton absorption in organic dyes or semiconductor quantum dots, lanthanide doped UCNPs involve real intermediate quantum states and convert infrared (IR) into visible light via sequential electronic excitation. The relatively high efficiency of this process even at low radiation flux makes UCNPs particularly attractive for many current and emerging areas of technology. The aim of this article is to highlight several recent advances in this rapidly growing field, emphasizing the relationships between structure and properties of UCNPs. Additionally, various strategies developed for the synthesis of UCNPs with a focus on the various synthetic approaches that yield high-quality monodisperse samples with controlled size, shape and crystalline phase are reviewed. Emerging synthetic approaches towards designed structure to improve the optical and electronic properties of UCNPs are discussed. Finally, recent examples of applications of UCNPs in biomedical and optoelectronics research, giving our own perspectives on future directions and emerging possibilities of the field are described.
Collapse
Affiliation(s)
- Chenglin Yan
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel Boulet, J3×1S2, Varennes, QC, Canada
| | - Haiguang Zhao
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel Boulet, J3×1S2, Varennes, QC, Canada
| | - Dmitrii F Perepichka
- Department of Chemistry, McGill University, H3A 0B8, Montreal, QC, Canada
- Center for Self-Assembled Chemical Structures, McGill University, H3A 0B8, Montreal, QC, Canada
| | - Federico Rosei
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel Boulet, J3×1S2, Varennes, QC, Canada
- Center for Self-Assembled Chemical Structures, McGill University, H3A 0B8, Montreal, QC, Canada
- Institute for Fundamental and Frontier Science, University of Electronic Science and Technology of China, Chengdu, PR China
| |
Collapse
|
4
|
Density dependent composition of InAs quantum dots extracted from grazing incidence x-ray diffraction measurements. Sci Rep 2015; 5:15732. [PMID: 26506865 PMCID: PMC4623704 DOI: 10.1038/srep15732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/28/2015] [Indexed: 11/08/2022] Open
Abstract
Epitaxial InAs quantum dots grown on GaAs substrate are being used in several applications ranging from quantum communications to solar cells. The growth mechanism of these dots also helps us to explore fundamental aspects of self-organized processes. Here we show that composition and strain profile of the quantum dots can be tuned by controlling in-plane density of the dots over the substrate with the help of substrate-temperature profile. The compositional profile extracted from grazing incidence x-ray measurements show substantial amount of inter-diffusion of Ga and In within the QD as a function of height in the low-density region giving rise to higher variation of lattice parameters. The QDs grown with high in-plane density show much less spread in lattice parameter giving almost flat density of In over the entire height of an average QD and much narrower photoluminescence (PL) line. The results have been verified with three different amounts of In deposition giving systematic variation of the In composition as a function of average quantum dot height and average energy of PL emission.
Collapse
|
5
|
Nozawa T, Takagi H, Watanabe K, Arakawa Y. Direct Observation of Two-Step Photon Absorption in an InAs/GaAs Single Quantum Dot for the Operation of Intermediate-Band Solar Cells. NANO LETTERS 2015; 15:4483-4487. [PMID: 26099362 DOI: 10.1021/acs.nanolett.5b00947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present the first direct observation of two-step photon absorption in an InAs/GaAs single quantum dot (QD) using photocurrent spectroscopy with two lasers. The sharp peaks of the photocurrent are shifted due to the quantum confined Stark effect, indicating that the photocurrent from a single QD is obtained. In addition, the intensity of the peaks depends on the power of the secondary laser. These results reveal the direct demonstration of the two-step photon absorption in a single QD. This is an essential result for both the fundamental operation and the realization of ultrahigh solar-electricity energy conversion in quantum dot intermediate-band solar cells.
Collapse
Affiliation(s)
- Tomohiro Nozawa
- †Institute for Nano Quantum Information Electronics and ‡Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
- §Advanced Technology Research Laboratories, SHARP Corporation, 2613-1 Ichinomoto-cho, Tenri, Nara 632-8567, Japan
| | - Hiroyuki Takagi
- †Institute for Nano Quantum Information Electronics and ‡Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Katsuyuki Watanabe
- †Institute for Nano Quantum Information Electronics and ‡Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Yasuhiko Arakawa
- †Institute for Nano Quantum Information Electronics and ‡Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| |
Collapse
|
6
|
Okano M, Sakamoto M, Teranishi T, Kanemitsu Y. Assessment of Hot-Carrier Effects on Charge Separation in Type-II CdS/CdTe Heterostructured Nanorods. J Phys Chem Lett 2014; 5:2951-2956. [PMID: 26278242 DOI: 10.1021/jz501564q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Charge separation in semiconducting materials is an essential process that determines the efficiency of photovoltaic devices and photocatalysts. Herein, we report the charge-separation dynamics in type-II CdS/CdTe heterostructured nanorods revealed by femtosecond transient-absorption (TA) measurements with a broad-band white-light probe. Under selective excitation of the CdTe segment, bleaching signals at the band gap energy of CdS were clearly observed with a rise component on a subpicosecond time scale, which indicates efficient electron transfer from CdTe to CdS. The pump-energy dependence of the TA dynamics shows that hot electrons rapidly relax to the bottom of the conduction band of CdTe, and then the electrons transfer to the CdS segment.
Collapse
Affiliation(s)
- Makoto Okano
- †Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Masanori Sakamoto
- †Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
- ‡Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Toshiharu Teranishi
- †Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yoshihiko Kanemitsu
- †Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
- §Japan Science and Technology Agency, CREST, Uji, Kyoto 611-0011, Japan
| |
Collapse
|