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Energy conversion approaches and materials for high-efficiency photovoltaics

Abstract

The past five years have seen significant cost reductions in photovoltaics and a correspondingly strong increase in uptake, with photovoltaics now positioned to provide one of the lowest-cost options for future electricity generation. What is becoming clear as the industry develops is that area-related costs, such as costs of encapsulation and field-installation, are increasingly important components of the total costs of photovoltaic electricity generation, with this trend expected to continue. Improved energy-conversion efficiency directly reduces such costs, with increased manufacturing volume likely to drive down the additional costs associated with implementing higher efficiencies. This suggests the industry will evolve beyond the standard single-junction solar cells that currently dominate commercial production, where energy-conversion efficiencies are fundamentally constrained by Shockley–Queisser limits to practical values below 30%. This Review assesses the overall prospects for a range of approaches that can potentially exceed these limits, based on ultimate efficiency prospects, material requirements and developmental outlook.

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Figure 1: Light absorption and emission, SQ limits, experimental energy-conversion efficiencies, radiative efficiencies and sunlight incident angles.
Figure 2: Multiple-junction cells, efficiency limits and highest experimental results.
Figure 3: Sub-bandgap absorption processes, equivalent circuit and limiting efficiencies.
Figure 4: Photon wavelength manipulation using luminescent concentrators and photon up- and down-conversion.
Figure 5: Schemes in which a single photon creates multiple photogenerated carriers.
Figure 6: Solar thermal conversion and conversion efficiencies.
Figure 7: Approaches that are thermodynamically related to solar thermal conversion.
Figure 8: Alternative high-efficiency approaches.

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References

  1. Chapin, D. M., Fuller, C. S. & Pearson, G. L. A new silicon p–n junction photocell for converting solar radiation into electrical power. J. Appl. Phys. 25, 676–677 (1954).

    CAS  Google Scholar 

  2. Prince, M. B. Silicon solar energy converters. J. Appl. Phys. 26, 534–540 (1955).

    Google Scholar 

  3. Loferski, J. J. Theoretical considerations governing the choice of the optimum semiconductor for photovoltaic solar energy conversion. J Appl. Phys. 27, 777–784 (1956).

    CAS  Google Scholar 

  4. Shockley, W. The theory of p–n junctions in semiconductors and p–n junction transistors. Bell Syst. Tech. J. 28, 435–489 (1949).

    Google Scholar 

  5. Shockley, W. & Queisser, H. J. Detailed balance limit of efficiency of p–n junction solar cells. J. Appl. Phys. 32, 510–519 (1961).

    CAS  Google Scholar 

  6. Green, M. A., Emery, K., Hishikawa, Y., Warta, W. & Dunlop, E. D. Solar cell efficiency tables (version 47). Prog. Photovoltaics 24, 3–11 (2016).

    Google Scholar 

  7. Green, M. A. Radiative efficiency of state-of-the-art photovoltaic cells. Prog. Photovoltaics 20, 472–476 (2012).

    CAS  Google Scholar 

  8. Green, M. A. Limits on the open circuit voltage and efficiency of silicon solar cells imposed by intrinsic Auger processes. IEEE Trans. Electron. Dev. ED-31, 671–678 (1984).

    CAS  Google Scholar 

  9. Richter, A., Hermle, M. & Glunz, W. Reassessment of the limiting efficiency for crystalline silicon solar cells . IEEE J. Photovol. 3, 1184–1191 (2013).

    Google Scholar 

  10. Mattheis, J., Werner, J. H. & Rau, U. Finite mobility effects on the radiative efficiency limit of pn-junction solar cells. Phys. Rev. B 77, 085203 (2008).

    Google Scholar 

  11. Green, M. A. Limiting photovoltaic efficiency under new ASTM G173 based reference spectra. Prog. Photovoltaics 20, 954–959 (2012).

    CAS  Google Scholar 

  12. Green, M. A. Third Generation Photovoltaics: Advanced Solar Energy Conversion (Springer, 2003).

    Google Scholar 

  13. Ross, R. T. Some thermodynamics of photochemical systems. J. Chem. Phys. 46, 4590–4593 (1967).

    CAS  Google Scholar 

  14. Wurfel, P. The chemical potential of radiation. J. Phys. C 15, 3967–3985 (1982).

    Google Scholar 

  15. Green, M. A. Analytical treatment of Trivich–Flinn and Shockley–Queisser photovoltaic efficiency limits using polylogarithms. Prog. Photovoltaics 20, 127–134 (2012).

    Google Scholar 

  16. Rau, U. Reciprocity relation between photovoltaic quantum efficiency and electroluminescent emission of solar cells. Phys. Rev. B 76, 085303 (2007).

    Google Scholar 

  17. Smestad, G., Ries, H., Winston, R. & Yablonovitch, E. The thermodynamic limits of light concentrators. Sol. Energ. Mater. 21, 99–111 (1990).

    CAS  Google Scholar 

  18. Carroll, J. J. Global transmissivity and diffuse fraction of solar radiation for clear and cloudy skies as measured and as predicted by bulk transmissivity models. Sol. Energy 35, 105–118 (1985).

    Google Scholar 

  19. Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37° Tilted Surface ASTM G173–03(2012) (ASTM International, 2012).

  20. Campbell, P. & Green, M. A. The limiting efficiency of silicon solar cells under concentrated sunlight. IEEE Trans. Electron. Dev. ED–33, 234–239 (1986).

    Google Scholar 

  21. Araújo, G. L. & Martí, A. Absolute limiting efficiencies for photovoltaic energy conversion. Sol. Energ. Mater. Sol. C. 33, 213–240 (1994).

    Google Scholar 

  22. Cornaro, C. & Andreotti, A. Influence of average photon energy index on solar irradiance characteristics and outdoor performance of photovoltaic modules. Prog. Photovoltaics 21, 996–1003 (2013).

    CAS  Google Scholar 

  23. Hamam, R. E., Celanovic, I. & Soljačić, M. Angular photonic band gap. Phys. Rev. A 83, 035806 (2011).

    Google Scholar 

  24. Kosten, E. D., Atwater, J. H., Parsons, J., Polman, A. & Atwater, H. A. Highly efficient GaAs solar cells by limiting light emission angle. Light Sci. Appl. 2, e45 (2013).

    Google Scholar 

  25. Höhn, O., Kraus, T., Bauhuis, G., Schwarz, U. T. & Bläsi, B. Maximal power output by solar cells with angular confinement. Opt. Express 22, A715–A722 (2014).

    Google Scholar 

  26. Chieng, C. & Green, M. A. Computer simulation of enhanced output from bifacial photovoltaic modules. Prog. Photovoltaics 1, 293–299 (1993).

    CAS  Google Scholar 

  27. Duran, C., Deuser, H., Harney, R. & Buck, T. Approaches to an improved IV and QE characterization of bifacial silicon solar cells and the prediction of their module performance. Energy Procedia 8, 88–93 (2011).

    Google Scholar 

  28. Skoplaki, E. & Palyvos, J. A. Operating temperature of photovoltaic modules: A survey of pertinent correlations. Renew. Energ. 34, 23–29 (2009).

    CAS  Google Scholar 

  29. Dupré, O., Vaillon, R. & Green, M. A. Physics of the temperature coefficients of solar cells. Sol. Energ. Mater. Sol. C. 140, 92–100 (2015).

    Google Scholar 

  30. Raman, A. P., Anoma, M. A., Zhu, L., Rephaeli, E. & Fan, S. Passive radiative cooling below ambient air temperature under direct sunlight. Nature 515, 540–544 (2014).

    CAS  Google Scholar 

  31. Gentle, A. R. & Smith, G. B. A subambient open roof surface under the mid-summer sun. Adv. Sci. 2, 1500119 (2015).

    Google Scholar 

  32. Zhu, L., Raman, A., Wang, K. X., Anoma, M. A. & Fan, S. Radiative cooling of solar cells. Optica 1, 32–38 (2014).

    CAS  Google Scholar 

  33. Rubin, M. Optical properties of soda lime silica glasses. Sol. Energ. Mater. 12, 275–288 (1985).

    CAS  Google Scholar 

  34. Zhao, J., Wang, A., Campbell, P. & Green, M. A. 22.7% efficient silicon photovoltaic modules with textured front surface. IEEE Trans. Electron. Dev. 46, 1495–1497 (1999).

    CAS  Google Scholar 

  35. Jackson, E. D. Areas for improvement of the semiconductor solar energy converter. Trans. Conf. on the Use of Solar Energy 5, 122–126 (1958).

    CAS  Google Scholar 

  36. Green, M. A. et al. 40% efficient sunlight to electricity conversion. Prog. Photovoltaics 23, 685–691 (2015).

    Google Scholar 

  37. De Vos, A. Detailed balance limit of the efficiency of tandem solar cells. J. Phys. D 13, 839–846 (1980).

    Google Scholar 

  38. Henry, C. H. Limiting efficiencies of ideal single and multiple energy gap terrestrial solar cells. J. Appl. Phys. 51, 4494–4500 (1980).

    CAS  Google Scholar 

  39. Marti, A & Araujo, G. L. Limiting efficiencies for photovoltaic energy conversion in multigap systems. Sol. Energ. Mater. Sol. C. 43, 203–222 (1996).

    CAS  Google Scholar 

  40. Chiu, P. T. et al. 35.8% space and 38.8% terrestrial 5J direct bonded cells. Proc. 40th IEEE Photovoltaic Specialist Conf. 11–13 (2014).

  41. Kayes, B. M., Zhang, L., Twist, R., Ding, I. K. & Higashi, G. S. Flexible thin-film tandem solar cells with >30% efficiency. IEEE J. Photovoltaics 4, 729–733 (2014).

    Google Scholar 

  42. Takamoto, T. Application of InGaP/GaAs/InGaAs triple junction solar cells to space use and concentrator photovoltaic. 40th IEEE Photovoltaic Specialists Conf. 1–5 (2014).

  43. Sai, H. et al. Triple-junction thin-film silicon solar cell fabricated on periodically textured substrate with a stabilized efficiency of 13.6%. Appl. Phys. Lett . 106, 213902 (2014).

    Google Scholar 

  44. Matsui, T. et al. Development of highly stable and efficient amorphous silicon based solar cells. Proc. 28th European Photovoltaic Solar Energy Conf. 2213–2217 (2013).

  45. Sai, H. et al. High-efficiency microcrystalline silicon solar cells on honeycomb textured substrates grown with high-rate VHF plasma-enhanced chemical vapor deposition. Jap. J. Appl. Phys. 54, 8S1 (2015).

    Google Scholar 

  46. New world record for solar cell efficiency at 46% French-German cooperation confirms competitive advantage of European photovoltaic industry Fraunhofer Institute for Solar Energy Systems (1 December 2014); http://go.nature.com/2bnQbeA

  47. Arvizu, D. E. Innovation: Enabling a Sustainable Energy Future (NREL, 2014); http://go.nature.com/2blCoSA

    Google Scholar 

  48. Green, M. A. Commercial progress and challenges for photovoltaics. Nat. Energy 1, 15015 (2016).

    Google Scholar 

  49. Snaith, H. From nanostructured to thin-film perovskite solar cells. 42nd IEEE Photovoltaic Specialists Conf. 14–19 (2015).

  50. Albrecht, S. et al. Monolithic perovskite/silicon-heterojunction tandem solar cells processed at low temperature. Energ. Environ. Sci. 9, 81–88 (2016).

    CAS  Google Scholar 

  51. Wolf, M. Limitations and possibilities for improvement of photovoltaic solar energy converters. Proc. IRE 48, 1246–1263 (1960).

    Google Scholar 

  52. Guttler, G. & Queisser, H. J. Impurity photovoltaic effect in silicon. Energ. Convers. 10, 51–55 (1970).

    Google Scholar 

  53. Barnham, K. & Duggan, G. A new approach to high-efficiency multi-band-gap solar cells. J. Appl. Phys. 67, 3490–3493 (1990).

    CAS  Google Scholar 

  54. Luque, A. & Marti, A. Increasing the efficiency of ideal solar cells by photon induced transitions at intermediate levels. Phys. Rev. Lett. 78, 5014–5017 (1997).

    CAS  Google Scholar 

  55. Brown, A. S. & Green, M. A. Intermediate band solar cell with many bands: Ideal performance. J. Appl. Phys. 94, 6150–6158 (2003).

    CAS  Google Scholar 

  56. Luque, A. Thermodynamic consistency of sub-bandgap absorbing solar cell proposals . IEEE Trans. Electron. Dev. 48, 2118–2124 (2001).

    Google Scholar 

  57. Ekins-Daukes, N. J. et al. High efficiency quantum well solar cells. 24th Workshop on Quantum Solar Energy Conversion (2012).

    Google Scholar 

  58. Brown, A. S. & Green, M. A. Impurity photovoltaic effect: Fundamental energy conversion efficiency limits. J. Appl. Phys. 92, 1329–1336 (2002).

    CAS  Google Scholar 

  59. Brown, A. S. & Green, M. A. Impurity photovoltaic effect with defect relaxation: Implications for low band gap semiconductors such as silicon. J. Appl. Phys. 96, 2603–2609 (2004).

    CAS  Google Scholar 

  60. Ramiro, I. & Marti, A. Review of experimental results related to the operation of intermediate band solar cells. IEEE J. Photovolt. 4, 736–748 (2014).

    Google Scholar 

  61. Weber, W. H. & Lambe, J. Luminescent greenhouse collector for solar radiation. Appl. Opt. 15, 2299–2300 (1976).

    CAS  Google Scholar 

  62. Goetzberger, A. & Greubel, W. Solar energy conversion with fluorescent concentrators. Appl. Phys. 14, 123–129 (1977).

    CAS  Google Scholar 

  63. Rau, U., Einsele, F. & Glaeser, C. Efficiency limits of photovoltaic fluorescent collectors. Appl. Phys. Lett. 87, 171101 (2005).

    Google Scholar 

  64. Richards, B. S., Shalav, A. & Corkish, R. P. A low escape-cone-loss luminescent solar concentrator. 19th Eur. Photovolt. Sol. Energ. Conf. (2004).

    Google Scholar 

  65. Slooff, L. H. et al. A luminescent solar concentrator with 7.1% power conversion efficiency. Phys. Stat. Sol. 2, 257–259 (2008).

    CAS  Google Scholar 

  66. Debije, M. Better luminescent solar panels in prospect. Nature 519, 298–299 (2015).

    CAS  Google Scholar 

  67. Trupke, T., Green, M. A. & Würfel, P. Improving solar cell efficiencies by the up-conversion of sub-band-gap light. J. Appl. Phys. 92, 4117–4122 (2002).

    CAS  Google Scholar 

  68. Trupke, T., Shalav, A., Richards, B. S., Wuerfel, P. & Green, M. A. Efficiency enhancement of solar cells by luminescent up-conversion of sunlight. Sol. Energ. Mater. Sol. C. 90, 3327–3338 (2006).

    CAS  Google Scholar 

  69. Trupke, T. Green, M. A. & Würfel, P. Improving solar cell efficiencies by down-conversion of high-energy photons. J. Appl. Phys. 92, 1668–1674 (2002).

    CAS  Google Scholar 

  70. Richards, B. S. Luminescent layers for enhanced silicon solar cell performance: Down-conversion. Sol. Energ. Mater. Sol. C. 90, 1189–1207 (2006).

    CAS  Google Scholar 

  71. Zhang, J. et al. Efficient quantum cutting in Tb3+/Yb3+ codoped a-NaYF4 single crystals grown by Bridgman method using KF flux for solar photovoltaic. IEEE J. Quant. Electron. 51, 7000206 (2015).

    Google Scholar 

  72. Wilkinson, F. J., Farmer, A. J. D. & Geist, J. The near ultraviolet yield of silicon. J. Appl. Phys. 54, 1172–1174 (1983).

    CAS  Google Scholar 

  73. Deb, S. & Saha, H. Secondary ionisation and its possible bearing on the performance of a solar cell. Solid State Electron. 15, 1389–1391 (1972).

    CAS  Google Scholar 

  74. Werner, J. H., Brendel, R. & Queisser, H. J. Radiative efficiency limit of terrestrial solar cells. Appl. Phys. Lett. 67, 1028–1030 (1995).

    CAS  Google Scholar 

  75. Beard, M., Luther, J. M., Semonin, O. & Nozik, A. J. Third generation photovoltaics based on multiple exciton generation in quantum confined semiconductors. Accounts Chem. Res. 46, 1252–1260 (2013).

    CAS  Google Scholar 

  76. Davis, N. J. L. K. et al. Multiple-exciton generation in lead selenide nanorod solar cells with external quantum efficiencies exceeding 120%. Nat. Commun. 6, 8259 (2015).

    CAS  Google Scholar 

  77. Hanna, M. C., Beard, M. C. & Nozik, A. J. Effect of solar concentration on the thermodynamic power conversion efficiency of quantum dot solar cells. J. Phys. Chem. Lett. 3, 2857–2862 (2012).

    CAS  Google Scholar 

  78. Semonin, O. E. et al. Peak external photocurrent quantum efficiency exceeding 100% via MEG in a quantum dot solar cell. Science 334, 1530–1533 (2011).

    CAS  Google Scholar 

  79. Perlin, J. Let It Shine: The 6,000-Year Story of Solar Energy (New World Library, 2013).

    Google Scholar 

  80. Des Vos, A. Endoreversible thermodynamics of solar energy conversion (Oxford Univ. Press, 1992).

    Google Scholar 

  81. Vining, C. B. An inconvenient truth about thermoelectrics. Nat. Mater. 8, 83–85 (2009).

    CAS  Google Scholar 

  82. Shakouri, A. Recent developments in semiconductor thermoelectric physics and materials. Annu. Rev. Mater. Res. 41, 399–431 (2011).

    CAS  Google Scholar 

  83. Stirling Energy Systems set new world record for solar-to-grid conversion efficiency. Sandia National Laboratories (12 February 2008); http://go.nature.com/2b2IFAH

  84. Barbee, J. Could this be the world's most efficient solar electricity system? The Guardian (13 May 2015); http://go.nature.com/2aRxMDa

    Google Scholar 

  85. Harder, N.-P. & Würfel, P. Theoretical limits of thermophotovoltaic solar energy conversion. Semicond. Sci. Tech. 18, S151–S157 (2003).

    CAS  Google Scholar 

  86. Anderson, D. J., Wong, W. A. & Tuttle, K. L. An overview and status of NASA's radioisotope power conversion technology NRA. Am. Inst. Aero. Astro. (2005).

  87. Ferrari, C., Melino, F., Pinelli, M., Spina, P. R. & Venturini, M. Overview and status of thermophotovoltaic systems . Energ. Proc. 45, 160–169 (2014).

    Google Scholar 

  88. Svetovoy, V. B. & Palasantzas, G. Graphene-on-silicon near-field thermophotovoltaic cell. Phys. Rev. Appl. 2, 034006 (2014).

    Google Scholar 

  89. Harder, N. & Green, M. A. Thermophotonics. Semicond. Sci. Tech. 18, S270–278 (2003).

    CAS  Google Scholar 

  90. Manor, A., Martin, L. L. & Rotschild, C. Conservation of photon rate in endothermic photoluminescence and its transition to thermal emission. Optica 2, 585–588 (2015).

    CAS  Google Scholar 

  91. Habedank, O. D. Analysis of Topaz II and space-R space nuclear power plants using a modified thermionic model MSc Thesis, Air Univ. (1993).

    Google Scholar 

  92. Yotter, R. A. A review of photodetectors for sensing light-emitting reporters in biological systems. IEEE Sens. J. 3, 288–303 (2003).

    CAS  Google Scholar 

  93. Schwede, J. W. et al. Photon-enhanced thermionic emission for solar concentrator systems. Nat. Mater. 9, 762–767 (2010).

    CAS  Google Scholar 

  94. Ross, R. T. & Nozik, A. J. Efficiency of hot-carrier solar energy converters. J. Appl. Phys. 53, 3813–3818 (1982).

    CAS  Google Scholar 

  95. Luque, A. & Marti, A. Electron-phonon energy transfer in hot-carrier solar cells. Sol. Energ. Mater. Sol. C. 94, 287–296 (2010).

    CAS  Google Scholar 

  96. Conibeer, G. et al. Hot carrier solar cell absorber prerequisites and candidate material systems. Sol. Energ. Mater. Sol. C. 135, 124–129 (2015).

    CAS  Google Scholar 

  97. Wurfel, P. Solar energy conversion with hot electrons from impact ionization. Sol. Energ. Mater. Sol. C. 46, 43–52 (1997).

    Google Scholar 

  98. Limpert, S., Bremner, S. & Linke, H. Reversible electron–hole separation in a hot carrier solar cell. New J. Phys. 17, 095004 (2015).

    Google Scholar 

  99. Würfel, P. Solar Olympic Conference (2000).

    Google Scholar 

  100. Humphrey, T. E. & Linke, H. Reversible thermoelectric nanomaterials. Phys. Rev. Lett. 94, 096601 (2005).

    CAS  Google Scholar 

  101. Takeda, Y. Quantum Dot Solar Cells Ch. 8 (eds Wu, J. & Wang, Z. M.) (Springer Science & Business Media, 2013).

    Google Scholar 

  102. Dimmock, J. A. R., Day, S., Kauer, M., Smith, K. & Heffernan, J. Demonstration of a hot-carrier photovoltaic cell. Prog. Photovolt. 22, 151–160 (2014).

    Google Scholar 

  103. Green, M. Third generation photovoltaics: Recent theoretical progress. 17th Eur. Photovolt. Sol. Energ. Conf. (2001).

    Google Scholar 

  104. Green, M. A. Time-asymmetric photovoltaics. Nano Lett. 12, 5985–5988 (2012).

    CAS  Google Scholar 

  105. Polman, A. & Atwater, A. Photonic design principles for ultrahigh-efficiency photovoltaics. Nat. Mater. 11, 174–177 (2012).

    CAS  Google Scholar 

  106. Callahan, D. M., Munday, J. N. & Atwater, H. A. Solar cell light trapping beyond the ray optic limit. Nano Lett. 12, 214–218 (2012).

    CAS  Google Scholar 

  107. Green, M. A. Enhanced evanescent mode light trapping in organic solar cells and other low index optoelectronic devices. Prog. Photovolt. Res. Appl. 19, 473–477 (2011).

    CAS  Google Scholar 

  108. Nechache, R. et al. Bandgap tuning of multiferroic oxide solar cells. Nat. Photon. 9, 61–67 (2015).

    CAS  Google Scholar 

  109. Green, M. A., Ho-Baillie, A. & Snaith, H. J. The emergence of perovskite solar cells. Nat. Photon. 8, 506–514 (2014).

    CAS  Google Scholar 

  110. Farrell, D. J. et al. Hot-carrier solar cell with optical energy selective contacts. Appl. Phys. Lett. 99, 111102 (2011).

    Google Scholar 

  111. Dimroth, F. High-efficiency solar cells from III–V compound semiconductors. Phys. Status Solidi C 3, 373–379 (2006).

    CAS  Google Scholar 

  112. Current and Future Costs of Photovoltaics: Long-term Scenarios for Market Development, System Prices and LCOE of Utility-scale PV Systems (Fraunhofer Institute for Solar Energy Systems, 2015); http://go.nature.com/2aYJCgc

  113. Yoshida, M., Ekins-Daukes, N. J., Farrell, D. J. & Phillips, C. C. Photon ratchet intermediate band solar cells. Appl. Phys. Lett. 100, 263902 (2012).

    Google Scholar 

  114. Christensen, O. Quantum efficiency of the internal photoelectric effect in silicon and germanium. J. Appl. Phys 47, 689–695 (1976).

    CAS  Google Scholar 

  115. Huang, H. Ferroelectric photovoltaics. Nat. Photon. 4, 134–135 (2010).

    CAS  Google Scholar 

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The authors acknowledge support from the Australian Government through the Australian Renewable Energy Agency (ARENA). The Australian Government does not accept responsibility for any information or advice contained herein.

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Green, M., Bremner, S. Energy conversion approaches and materials for high-efficiency photovoltaics. Nature Mater 16, 23–34 (2017). https://doi.org/10.1038/nmat4676

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