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Journal ArticleDOI

Carrier population control and surface passivation in solar cells

TL;DR: In this article, different approaches to suppress surface recombination and to manipulate the concentration of charge carriers by means of doping, work function and charge are discussed, as well as some of the many surface-passivating contacts that are being developed for silicon solar cells.
About: This article is published in Solar Energy Materials and Solar Cells.The article was published on 2018-09-01 and is currently open access. It has received 102 citations till now. The article focuses on the topics: Charge carrier & Passivation.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the influence of the MoOx and intrinsic a-Si:H thicknesses on current-voltage properties and discuss transport and performance-loss mechanisms is discussed. But the authors focus on the front-side hole-selective layer.

163 citations

Journal ArticleDOI
TL;DR: In this paper, the development status of high-efficiency crystalline silicon (c-Si) heterojunction solar cells, from the materials to devices, mainly including hydrogenated amorphous silicon (a-Si:H) based silicon heterjunction technology, polycrystalline silicon based carrier selective passivating contact technology, metal compounds and organic materials based dopant-free contact technology are reviewed.
Abstract: Photovoltaic (PV) technology offers an economic and sustainable solution to the challenge of increasing energy demand in times of global warming. The world PV market is currently dominated by the homo-junction crystalline silicon (c-Si) PV technology based on high temperature diffused p-n junctions, featuring a low power conversion efficiency (PCE). Recent years have seen the successful development of Si heterojunction technologies, boosting the PCE of c-Si solar cells over 26%. This article reviews the development status of high-efficiency c-Si heterojunction solar cells, from the materials to devices, mainly including hydrogenated amorphous silicon (a-Si:H) based silicon heterojunction technology, polycrystalline silicon (poly-Si) based carrier selective passivating contact technology, metal compounds and organic materials based dopant-free passivating contact technology. The application of silicon heterojunction solar cells for ultra-high efficiency perovskite/c-Si and III-V/c-Si tandem devices is also reviewed. In the last, the perspective, challenge and potential solutions of silicon heterojunction solar cells, as well as the tandem solar cells are discussed.

112 citations

Journal ArticleDOI
21 Apr 2021-Joule
TL;DR: In this paper, the authors provide a perspective of the remaining challenges and potential of poly-Si junctions to transform the PV industry, including those associated with the cost of and damage to the polySi layers due to the cell's metallization process.

69 citations

Journal ArticleDOI
TL;DR: In this paper , the authors survey the key changes related to materials and industrial processing of silicon PV components and discuss what it will take for other PV technologies to compete with silicon on the mass market.
Abstract: Crystalline silicon (c-Si) photovoltaics has long been considered energy intensive and costly. Over the past decades, spectacular improvements along the manufacturing chain have made c-Si a low-cost source of electricity that can no longer be ignored. Over 125 GW of c-Si modules have been installed in 2020, 95% of the overall photovoltaic (PV) market, and over 700 GW has been cumulatively installed. There are some strong indications that c-Si photovoltaics could become the most important world electricity source by 2040–2050. In this Review, we survey the key changes related to materials and industrial processing of silicon PV components. At the wafer level, a strong reduction in polysilicon cost and the general implementation of diamond wire sawing has reduced the cost of monocrystalline wafers. In parallel, the concentration of impurities and electronic defects in the various types of wafers has been reduced, allowing for high efficiency in industrial devices. Improved cleanliness in production lines, increased tool automation and improved production technology and cell architectures all helped to increase the efficiency of mainstream modules. Efficiency gains at the cell level were accompanied by an increase in wafer size and by the introduction of advanced assembly techniques. These improvements have allowed a reduction of cell-to-module efficiency losses and will accelerate the yearly efficiency gain of mainstream modules. To conclude, we discuss what it will take for other PV technologies to compete with silicon on the mass market. Crystalline silicon solar cells are today’s main photovoltaic technology, enabling the production of electricity with minimal carbon emissions and at an unprecedented low cost. This Review discusses the recent evolution of this technology, the present status of research and industrial development, and the near-future perspectives.

67 citations

Journal ArticleDOI
TL;DR: Kohler et al. as mentioned in this paper proposed a passivating contact based on a double layer of nanocrystalline silicon carbide that overcomes the trade-offs of conductivity, defect passivation and optical transparency.
Abstract: A highly transparent passivating contact (TPC) as front contact for crystalline silicon (c-Si) solar cells could in principle combine high conductivity, excellent surface passivation and high optical transparency. However, the simultaneous optimization of these features remains challenging. Here, we present a TPC consisting of a silicon-oxide tunnel layer followed by two layers of hydrogenated nanocrystalline silicon carbide (nc-SiC:H(n)) deposited at different temperatures and a sputtered indium tin oxide (ITO) layer (c-Si(n)/SiO2/nc-SiC:H(n)/ITO). While the wide band gap of nc-SiC:H(n) ensures high optical transparency, the double layer design enables good passivation and high conductivity translating into an improved short-circuit current density (40.87 mA cm−2), fill factor (80.9%) and efficiency of 23.99 ± 0.29% (certified). Additionally, this contact avoids the need for additional hydrogenation or high-temperature postdeposition annealing steps. We investigate the passivation mechanism and working principle of the TPC and provide a loss analysis based on numerical simulations outlining pathways towards conversion efficiencies of 26%. Passivating contacts hold promise for silicon solar cells yet the simultaneous optimization of conductivity, defect passivation and optical transparency remains challenging. Now Kohler et al. devise a passivating contact based on a double layer of nanocrystalline silicon carbide that overcomes these trade-offs.

65 citations

References
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Journal ArticleDOI
TL;DR: In this article, the recombination kinetics in highly doped p− and n−type silicon were investigated at 77, 300, and 400 K through the radiative band-to-band recombination.
Abstract: The recombination kinetics in highly doped p‐ and n‐type silicon has been investigated at 77, 300, and 400 K through the radiative band‐to‐band recombination. The minority‐carrier lifetime depends quadratically on the doping concentration as expected for Auger recombination. The Auger coefficients at 300 K for p‐ and n‐type silicon are found to be Cp=9.9×10−32 cm6 s−1 and Cn=2.8×10−31 cm6 s−1. They are nearly independent of temperature in the range investigated. The Auger coefficient in highly excited pure silicon at 4.2 K (electron‐hole drops) is essentially the same as in highly doped silicon.

774 citations

Journal ArticleDOI
TL;DR: In this article, the influence of the improved state-of-the-art parameters on the limiting efficiency for crystalline silicon solar cells under 1-sun illumination at 25°C, by following the narrow-base approximation to model ideal solar cells was analyzed.
Abstract: Recently, several parameters relevant for modeling crystalline silicon solar cells were improved or revised, e.g., the international standard solar spectrum or properties of silicon such as the intrinsic recombination rate and the intrinsic carrier concentration. In this study, we analyzed the influence of these improved state-of-the-art parameters on the limiting efficiency for crystalline silicon solar cells under 1-sun illumination at 25°C, by following the narrow-base approximation to model ideal solar cells. We also considered bandgap narrowing, which was not addressed so far with respect to efficiency limitation. The new calculations that are presented in this study result in a maximum theoretical efficiency of 29.43% for a 110-μm-thick solar cell made of undoped silicon. A systematic calculation of the I-V parameters as a function of the doping concentration and the cell thickness together with an analysis of the loss current at maximum power point provides further insight into the intrinsic limitations of silicon solar cells.

755 citations

Book
01 Jan 2009
TL;DR: In this article, the basic structure of solar cells and the limitations on energy conversion in solar cells are discussed, as well as some concepts for improving the efficiency of the solar cells.
Abstract: 1 Problems of the Energy Economy 2 Photons 3 Semiconductors 4 Conversion of Thermal Radiation into Chemical Energy 5 Conversion of Chemical Energy into Electrical Energy 6 Basic Structure of Solar Cells 7 Limitations on Energy Conversion in Solar Cells 8 Concepts for Improving the Efficiency of Solar Cells 9 Prospects for the Future

464 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that the necessary selectivity is achieved by differences in the conductivities of electrons and holes in two distinct regions of the device, which, for one charge carrier, allows transport to one contact and block transport to the other contact.
Abstract: The selective transport of electrons and holes to the two terminals of a solar cell is often attributed to an electric field, although well-known physics states that they are driven by gradients of quasi-Fermi energies. However, in an illuminated semiconductor, these forces are not selective, and they drive both charge carriers toward both contacts. This paper shows that the necessary selectivity is achieved by differences in the conductivities of electrons and holes in two distinct regions of the device, which, for one charge carrier, allows transport to one contact and block transport to the other contact.

338 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the application of transparent MoOx films deposited by thermal evaporation directly onto crystalline silicon (c-Si) to create hole-conducting contacts for silicon solar cells.
Abstract: This letter examines the application of transparent MoOx (x < 3) films deposited by thermal evaporation directly onto crystalline silicon (c-Si) to create hole-conducting contacts for silicon solar cells. The carrier-selectivity of MoOx based contacts on both n- and p-type surfaces is evaluated via simultaneous consideration of the contact recombination parameter J0c and the contact resistivity ρc. Contacts made to p-type wafers and p+ diffused regions achieve optimum ρc values of 1 and 0.2 mΩ·cm2, respectively, and both result in a J0c of ∼200 fA/cm2. These values suggest that significant gains can be made over conventional hole contacts to p-type material. Similar MoOx contacts made to n-type silicon result in higher J0c and ρc with optimum values of ∼300 fA/cm2 and 30 mΩ·cm2 but still offer significant advantages over conventional approaches in terms of contact passivation, optical properties, and device fabrication.

274 citations