Improved device performance of InAs∕GaAs quantum dot solar cells with GaP strain compensation layers

2010 35th IEEE Photovoltaic Specialists Conference

Linares

et al. 2010

Several groups have reported on intermediate band solar cells (IBSC) fabricated with InAs/GaAs quantum dots (QD) which exhibit quantum efficiencies (QE) for sub-bandgap photon energies. However, this QE is produced by the absorption of photons only through valence band (VB) to intermediate band (IB) transitions. The absorption of photons of that energy in IB to conduction band (CB) transitions is weak and is usually replaced by carrier escape. This mechanism is incompatible with the preservation of the output voltage, and therefore, it cannot lead to the high efficiencies predicted by the IBSC model. In this work, we discuss the contribution of thermal and tunneling mechanisms to IB-CB carrier escape in current QD-IBSCs. It is experimentally demonstrated that in QD-IBSC prototypes where tunnel escape has been eliminated, the sub-bandgap QE is suppressed at sufficiently low temperatures, and when this occurs, the only limit for the open-circuit voltage (VOC) is the fundamental semiconductor bandgap, as stated by the IBSC theoretical model.

Section: Introductionmentioning

confidence: 55%

Advances in quantum dot intermediate band solar cells

2010 35th IEEE Photovoltaic Specialists Conference

Linares

et al. 2010

“…One is to continue using the III-V S-K approach, but introducing important variations in the QD material system; for example, by adding N to the dot and substituting the GaAs host by a wider gap material (GaInP, AlGaAs) as proposed in [15]. To maintain the S-K approach means most likely to keep fighting the effects of strain with techniques as reported in [8,9,16,17]. The second strategy is to move away from the InAs/GaAs QD family towards a completely different set of materials.…”

Section: Introductionmentioning

confidence: 99%

The lead salt quantum dot intermediate band solar cell

2011 37th IEEE Photovoltaic Specialists Conference

Ĺuque

2011

“…Most of QD-IBSC prototypes to date have been manufactured using the In(Ga)As/GaAs QD system. To tackle the problem of the accumulated strain in the QD-stack and improve the material quality, a small amount of N [33], P [34]- [36] or Sb [37] has been included in some cases in the host material. Although the bandgap distribution in this material is not optimal for an IBSC, this system was already technologically mature and, hence, the best candidate for testing the IB principles.…”

Section: A Quantum Dotsmentioning

confidence: 99%

Review of Experimental Results Related to the Operation of Intermediate Band Solar Cells

Ramiro

et al. 2014

IEEE J. Photovoltaics

Abstract-The intermediate band solar cell (IBSC) has drawn the attention of the scientific community as a means to achieve high-efficiency solar cells. Complete IBSC devices have been manufactured using quantum dots, highly mismatched alloys, or bulk materials with deep-level impurities. Characterization of these devices has led, among other experimental results, to the demonstration of the two operating principles of an IBSC: the production of the photocurrent from the absorption of two below bandgap energy photons and the preservation of the output voltage of the solar cell. This study offers a thorough compilation of the most relevant reported results for the variety of technologies investigated and provides the reader with an updated record of IBSC experimental achievements. A table condensing the reported experimental results is presented, which provides information at a glance about achievements, as well as pending results, for every studied technology.