UNLABELLED: Nano-patterning the semiconducting photoactive layer/back electrode interface of organic photovoltaic devices is a widely accepted approach to enhance the power conversion efficiency through the exploitation of numerous photonic and plasmonic effects. Yet, nano-patterning the semiconductor/metal interface leads to intertwined effects that impact the optical as well as the electrical characteristic of solar cells. In this work we aim to disentangle the optical and electrical effects of a nano-structured semiconductor/metal interface on the device performance. For this, we use an inverted bulk heterojunction P3HT:PCBM solar cell structure, where the nano-patterned photoactive layer/back electrode interface is realized by patterning the active layer with sinusoidal grating profiles bearing a periodicity of 300 nm or 400 nm through imprint lithography while varying the photoactive layer thickness (L PAL ) between 90 and 400 nm. The optical and electrical device characteristics of nano-patterned solar cells are compared to the characteristics of control devices, featuring a planar photoactive layer/back electrode interface. We find that patterned solar cells show for an enhanced photocurrent generation for a L PAL above 284 nm, which is not observed when using thinner active layer thicknesses. Simulating the optical characteristic of planar and patterned devices through a finite-difference time-domain approach proves for an increased light absorption in presence of a patterned electrode interface, originating from the excitation of propagating surface plasmon and dielectric waveguide modes. Evaluation of the external quantum efficiency characteristic and the voltage dependent charge extraction characteristics of fabricated planar and patterned solar cells reveals, however, that the increased photocurrents of patterned devices do not stem from an optical enhancement but from an improved charge carrier extraction efficiency in the space charge limited extraction regime. Presented findings clearly demonstrate that the improved charge extraction efficiency of patterned solar cells is linked to the periodic surface corrugation of the (back) electrode interface. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00339-023-06492-6.

AIT Austrian Institute of Technology GmbH BioSensor Technologies Konrad Lorenz Straße 24 3430 Tulln Austria

FZU Institute of Physics Czech Academy of Sciences Na Slovance 182 21 Prague Czech Republic

Helmholtz Zentrum Berlin für Materialien und Energie GmbH Hahn Meitner Platz 1 14109 Berlin Germany

Institut für Physik Institut für Chemie and IRIS Adlershof Humboldt Universität zu Berlin Zum Großen Windkanal 2 12489 Berlin Germany

Institute of Surface Technologies and Photonics Joanneum Research Forschungsges mbH Franz Pichler Straße 30 8160 Weiz Austria

Zobrazit více v PubMed

Riede M, Spoltore D, Leo K. Organic solar cells—the path to commercial success. Adv Energy Mater. 2021;11(1):1–10. doi: 10.1002/aenm.202002653. DOI

Xue R, Zhang J, Li Y, Li Y. Organic solar cell materials toward commercialization. Small. 2018;14(41):1–24. doi: 10.1002/smll.201801793. PubMed DOI

Yang F, Huang Y, Li Y, Li Y. Large-area flexible organic solar cells. npj Flex Electron. 2021;5(1):1–12. doi: 10.1038/s41528-021-00128-6. DOI

Hong L, Yao H, Cui Y, Ge Z, Hou J. Recent advances in high-efficiency organic solar cells fabricated by eco-compatible solvents at relatively large-area scale. APL Mater. 2020 doi: 10.1063/5.0027948. DOI

Ghosekar IC, Patil GC. Review on performance analysis of P3HT:PCBM-based bulk heterojunction organic solar cells. Semicond Sci Technol. 2021 doi: 10.1088/1361-6641/abe21b. DOI

Sadoogi N, Rostami A, Faridpak B, Farrokhifar M. Performance analysis of organic solar cells: opto-electrical modeling and simulation. Eng Sci Technol Int J. 2021;24(1):229–235. doi: 10.1016/j.jestch.2020.08.006. DOI

Ajayan J, Nirmal D, Mohankumar P, Saravanan M, Jagadesh M, Arivazhagan L. A review of photovoltaic performance of organic/inorganic solar cells for future renewable and sustainable energy technologies. Superlattices Microstruct. 2020;143:106549. doi: 10.1016/j.spmi.2020.106549. DOI

Zhang Y, Wu B, He Y, et al. Layer-by-layer processed binary all-polymer solar cells with efficiency over 16% enabled by finely optimized morphology. Nano Energy. 2022;93:106858. doi: 10.1016/j.nanoen.2021.106858. DOI

Liu Q, Jiang Y, Jin K, et al. 18% Efficiency organic solar cells. Sci Bull. 2020;65(4):272–275. doi: 10.1016/j.scib.2020.01.001. PubMed DOI

Amalathas AP, Alkaisi MM. Nanostructures for light trapping in thin film solar cells. Micromachines. 2019;10(9):1–18. doi: 10.3390/mi10090619. PubMed DOI PMC

Guo CF, Sun T, Cao F, Liu Q, Ren Z. Metallic nanostructures for light trapping in energy-harvesting devices. Light Sci Appl. 2014;3(4):e161–e161. doi: 10.1038/lsa.2014.42. DOI

Mokkapati S, Catchpole KR. Nanophotonic light trapping in solar cells. J Appl Phys. 2012 doi: 10.1063/1.4747795. DOI

Yu Z, Raman A, Fan S. Fundamental limit of nanophotonic light trapping in solar cells. Proc Natl Acad Sci USA. 2010;107(41):17491–17496. doi: 10.1073/pnas.1008296107. PubMed DOI PMC

Green M, Emery K, Hishikawa Y, et al. Solar cell efficiency tables (version 40) Ieee Trans Fuzzy Syst. 2012;20(6):1114–1129. doi: 10.1002/pip.1038. DOI

Petoukhoff CE, Shen Z, Jain M, Chang A, O’Carroll DM. Plasmonic electrodes for bulk-heterojunction organic photovoltaics: a review. J Photon. Energy. 2015;5(1):057002. doi: 10.1117/1.jpe.5.057002. DOI

Atwater HA, Polman A. Plasmonics for improved photovoltaic devices. Nat Mater. 2010;9(3):205–213. doi: 10.1038/nmat2629. PubMed DOI

Ahn S, Rourke D, Park W. Plasmonic nanostructures for organic photovoltaic devices. J. Opt. (United Kingdom). 2016;18(3):33001. doi: 10.1088/2040-8978/18/3/033001. DOI

Gan Q, Bartoli FJ, Kafafi ZH. Plasmonic-enhanced organic photovoltaics: breaking the 10% efficiency barrier. Adv Mater. 2013;25(17):2385–2396. doi: 10.1002/adma.201203323. PubMed DOI

Shen H, Maes B. Combined plasmonic gratings in organic solar cells. Opt Express. 2011;19(S6):A1202. doi: 10.1364/oe.19.0a1202. PubMed DOI

Sefunc MA, Okyay AK, Demir HV. Plasmonic backcontact grating for P3HT:PCBM organic solar cells enabling strong optical absorption increased in all polarizations. Opt Express. 2011;19(15):14200–14209. doi: 10.1364/OE.19.014200. PubMed DOI

Toan Dang P, Nguyen TK, Le KQ. Revisited design optimization of metallic gratings for plasmonic light-trapping enhancement in thin organic solar cells. Opt Commun. 2017;382:241–245. doi: 10.1016/j.optcom.2016.07.080. DOI

Wen L, Sun F, Chen Q. Cascading metallic gratings for broadband absorption enhancement in ultrathin plasmonic solar cells. Appl. Phys. Lett. 2014 doi: 10.1063/1.4871584. DOI

Yousif B, Abo-Elsoud MEA, Marouf H. Triangle grating for enhancement the efficiency in thin film photovoltaic solar cells. Opt. Quantum Electron. 2019;51(8):1–11. doi: 10.1007/s11082-019-1987-5. DOI

Chiu NF, Hou CH, Cheng CJ, Tsai FY. Plasmonic circular nanostructure for enhanced light absorption in organic solar cells. Int. J. Photoenergy. 2013 doi: 10.1155/2013/502576. DOI

Chriki R, Yanai A, Shappir J, Levy U. Enhanced efficiency of thin film solar cells using a shifted dual grating plasmonic structure. Opt Express. 2013;21(S3):A382. doi: 10.1364/oe.21.00a382. PubMed DOI

Bi YG, Feng J, Chen Y, et al. Dual-periodic-corrugation-induced broadband light absorption enhancement in organic solar cells. Org Electron. 2015;27:167–172. doi: 10.1016/j.orgel.2015.09.021. DOI

Li X, Choy WCH, Ren X, Xin J, Lin P, Leung DCW. Polarization-independent efficiency enhancement of organic solar cells by using 3-dimensional plasmonic electrode. Appl. Phys. Lett. 2013;102(15):153304. doi: 10.1063/1.4802261. DOI

Li K, Haque S, Martins A, et al. Light trapping in solar cells: simple design rules to maximize absorption. Optica. 2020;7(10):1377. doi: 10.1364/optica.394885. DOI

Wang C, Yu S, Chen W, Sun C. Highly efficient light-trapping structure design inspired by natural evolution. Sci. Rep. 2013 doi: 10.1038/srep01025. PubMed DOI PMC

Khan I, Keshmiri H, Kolb F, Dimopoulos T, List-Kratochvil EJWW, Dostalek J. Multidiffractive broadband plasmonic absorber. Adv Opt Mater. 2016;4(3):435–443. doi: 10.1002/adom.201500508. DOI

Lin A, Phillips J. Optimization of random diffraction gratings in thin-film solar cells using genetic algorithms. Sol. Energy Mater. Sol. Cells. 2008;92(12):1689–1696. doi: 10.1016/j.solmat.2008.07.021. DOI

Li XH, Sha WEII, Choy WCHH, Fung DDSS, Xie FX. Efficient inverted polymer solar cells with directly patterned active layer and silver back grating. J. Phys. Chem C. 2012;116(12):7200–7206. doi: 10.1021/jp211237c. DOI

Wang DH, Seifter J, Park JH, Choi DG, Heeger AJ. Effi ciency increase in flexible bulk heterojunction solar cells with a nano-patterned indium zinc oxide anode. Adv Energy Mater. 2012;2(11):1319–1322. doi: 10.1002/aenm.201200349. DOI

Hsu CM, Battaglia C, Pahud C, et al. High-efficiency amorphous silicon solar cell on a periodic nanocone back reflector. Adv. Energy Mater. 2012;2(6):628–633. doi: 10.1002/aenm.201100514. DOI

Oh J, Yuan HC, Branz HM. An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures. Nat. Nanotechnol. 2012;7(11):743–748. doi: 10.1038/nnano.2012.166. PubMed DOI

Na S-II, Kim S-SS, Jo J, et al. Efficient polymer solar cells with surface relief gratings fabricated by simple soft lithography. Adv. Funct. Mater. 2008;18(24):3956–3963. doi: 10.1002/adfm.200800683. DOI

Liu Y, Tippets CA, Kirsch C, Mitran S, Samulski ET, Lopez R. Balance between light trapping and charge carrier collection: electro-photonic optimization of organic photovoltaics with ridge-patterned back electrodes. J. Appl. Phys. 2013 doi: 10.1063/1.4812235. DOI

Sha WEI, Li X, Choy WCH. Breaking the space charge limit in organic solar cells by a novel plasmonic-electrical concept. Sci Rep. 2014;4(1):1–10. doi: 10.1038/srep06236. PubMed DOI PMC

Choy WCH, Ren X. Plasmon-electrical effects on organic solar cells by incorporation of metal nanostructures. IEEE J. Sel. Top Quantum Electron. 2016 doi: 10.1109/JSTQE.2015.2442679. DOI

Pivrikas A, Sarifciftci NS, Juska G, Österbacka R. A review of charge transport and recombination in polymer/fullerene organic solar cells. Prog. Photovoltaics Res. Appl. 2007;15:677–696. doi: 10.1002/pip.791. DOI

Stolterfoht M, Armin A, Philippa B, et al. Photocarrier drift distance in organic solar cells and photodetectors. Sci. Rep. 2015;5(1):1–7. doi: 10.1038/srep09949. PubMed DOI PMC

König TAF, Ledin PA, Kerszulis J, et al. Electrically tunable plasmonic behavior of nanocube-polymer nanomaterials induced by a redox-active electrochromic polymer. ACS Nano. 2014;8(6):6182–6192. doi: 10.1021/nn501601e. PubMed DOI

Zhang Y, Cui Y, Wang W, et al. Absorption enhancement in organic solar cells with a built-in short-pitch plasmonic grating. Plasmonics. 2015;10(4):773–781. doi: 10.1007/s11468-014-9864-3. DOI

Yang HU, D’Archangel J, Sundheimer ML, Tucker E, Boreman GD, Raschke MB. Optical dielectric function of silver. Phys. Rev. B. 2015;91(23):235137. doi: 10.1103/PhysRevB.91.235137. DOI

Kim JB, Guan ZL, Shu AL, Kahn A, Loo YL. Annealing sequence dependent open-circuit voltage of inverted polymer solar cells attributable to interfacial chemical reaction between top electrodes and photoactive layers. Langmuir. 2011;27(17):11265–11271. doi: 10.1021/la202178p. PubMed DOI

Ghosekar IC, Patil GC. Thermal stability analysis of buffered layer P3HT/P3HT:PCBM organic solar cells. IET Optoelectron. 2019;13(5):240–246. doi: 10.1049/iet-opt.2018.5173. DOI

Kim H, So WW, Moon SJ. The importance of post-annealing process in the device performance of poly(3-hexylthiophene): Methanofullerene polymer solar cell. Sol Energy Mater Sol Cells. 2007;91(7):581–587. doi: 10.1016/j.solmat.2006.11.010. DOI

Dang MT, Hirsch L, Wantz G. P3HT:PCBM, best seller in polymer photovoltaic research. Adv. Mater. 2011;23(31):3597–3602. doi: 10.1002/adma.201100792. PubMed DOI

Chandrasekaran N, Kumar A, Thomsen L, Kabra D, McNeill CR. High performance as-cast P3HT:PCBM devices: understanding the role of molecular weight in high regioregularity P3HT. Mater. Adv. 2021;2(6):2045–2054. doi: 10.1039/d0ma00738b. DOI

Meitzner R, Faber T, Alam S, et al. Impact of P3HT materials properties and layer architecture on OPV device stability. Sol. Energy Mater. Sol. Cells. 2019;202:110151. doi: 10.1016/j.solmat.2019.110151. DOI

Loeza-Poot M, Méndez-Hernández J, Oviedo-Mendoza M, Mis-Fernández R, Peña JL, Hernández-Rodríguez E. Effects of the processing variables on the optical properties of P3HT:PCBM absorber layer: an statical point of view. Org. Electron. 2022 doi: 10.1016/j.optmat.2023.113514. DOI

Nam S, Jang J, Cha H, et al. Effects of direct solvent exposure on the nanoscale morphologies and electrical characteristics of PCBM-based transistors and photovoltaics. J. Mater. Chem. 2012;22(12):5543–5549. doi: 10.1039/c2jm15260f. DOI

Kadem B, Hassan A, Cranton W. Efficient P3HT:PCBM bulk heterojunction organic solar cells; effect of post deposition thermal treatment. J. Mater. Sci. Mater. Electron. 2016;27(7):7038–7048. doi: 10.1007/s10854-016-4661-8. DOI

Munshi J, Balasubramanian G. Investigating blend morphology of P3HT:PCBM bulk heterojunction solar cells by classical atomistic simulations–progress and prospects. Soft. Mater. 2020;18(2–3):163–176. doi: 10.1080/1539445X.2019.1711397. DOI

Choi JK, Jin JK, Jin ML, An CJ, Jung HT. Comparison of blend morphologies of the nano-patterned photoactive films via two different techniques: thermal-assisted and solvent-assisted soft-nanoimprint lithography. RSC Adv. 2014;4(24):12302–12308. doi: 10.1039/c3ra46489j. DOI

Rafique S, Abdullah SM, Sulaiman K, Iwamoto M. Fundamentals of bulk heterojunction organic solar cells: an overview of stability/degradation issues and strategies for improvement. Renew. Sustain. Energy Rev. 2017;2018(84):43–53. doi: 10.1016/j.rser.2017.12.008. DOI

Sievers DW, Shrotriya V, Yang Y. Modeling optical effects and thickness dependent current in polymer bulk-heterojunction solar cells. J. Appl. Phys. 2006;100(11):114509. doi: 10.1063/1.2388854. DOI

Lenes M, Morana M, Brabec CJ, Blom PWMM. Recombination-limited photocurrents in low bandgap polymer/fullerene solar cells. Adv. Funct. Mater. 2009;19(7):1106–1111. doi: 10.1002/adfm.200801514. DOI

Namkoong G, Kong J, Samson M, Hwang IW, Lee K. Active layer thickness effect on the recombination process of PCDTBT:PC71BM organic solar cells. Org. Electron. 2013;14(1):74–79. doi: 10.1016/j.orgel.2012.10.025. DOI

Small CE, Tsang S-W, Chen S, et al. Loss mechanisms in thick-film low-bandgap polymer solar cells. Adv. Energy Mater. 2013;3(7):909–916. doi: 10.1002/aenm.201201114. DOI

Kaienburg P, Rau U, Kirchartz T. Extracting information about the electronic quality of organic solar-cell absorbers from fill factor and thickness. Phys. Rev. Appl. 2016;6(2):024001. doi: 10.1103/PhysRevApplied.6.024001. DOI

Udum Y, Denk P, Adam G, et al. Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer. Org. Electron Phys. Mater. Appl. 2014;15(5):997–1001. doi: 10.1016/j.orgel.2014.02.009. PubMed DOI PMC

Maier SA. Plasmonics: fundamentals and applications. New York: Springer, US; 2007.

Barnes WL, Dereux A, Ebbesen TW. Surface plasmon subwavelength optics. Nature. 2003;424(6950):824–830. doi: 10.1038/nature01937. PubMed DOI

Tvingstedt K, Tang Z, Inganäs O. Light trapping with total internal reflection and transparent electrodes in organic photovoltaic devices. Appl. Phys. Lett. 2012 doi: 10.1063/1.4759125. DOI

Disney CER, Pillai S, Green MA. The impact of parasitic loss on solar cells with plasmonic nano-textured rear reflectors. Sci. Rep. 2017;7(1):1–10. doi: 10.1038/s41598-017-12896-1. PubMed DOI PMC

Zou Y, Sheng X, Xia K, Fu H, Hu J. Parasitic loss suppression in photonic and plasmonic photovoltaic light trapping structures. Opt Express. 2014;22(S4):A1197. doi: 10.1364/oe.22.0a1197. PubMed DOI

Cowan SR, Wang J, Yi J, Lee YJ, Olson DC, Hsu JWP. Intensity and wavelength dependence of bimolecular recombination in P3HT:PCBM solar cells: a white-light biased external quantum efficiency study. J Appl Phys. 2013;113(15):154504. doi: 10.1063/1.4801920. DOI

Lakhwani G, Rao A, Friend RH. Bimolecular recombination in organic photovoltaics. Annu. Rev. Phys. Chem. 2014;65(1):557–581. doi: 10.1146/annurev-physchem-040513-103615. PubMed DOI

Goodman AM, Rose A. Double extraction of uniformly generated electron-hole pairs from insulators with noninjecting contacts. J. Appl. Phys. 1971;42(7):2823–2830. doi: 10.1063/1.1660633. DOI

Mihailetchi VD, Wildeman J, Blom PWM. Space-charge limited photocurrent. Phys. Rev. Lett. 2005;94(12):1–4. doi: 10.1103/PhysRevLett.94.126602. PubMed DOI

Koster LJA, Mihailetchi VD, Xie H, Blom PWM. Origin of the light intensity dependence of the short-circuit current of polymer/fullerene solar cells. Appl Phys Lett. 2005;87(20):1–3. doi: 10.1063/1.2130396. DOI

Wilken S, Sandberg OJ, Scheunemann D, Österbacka R. Watching space charge build up in an organic solar cell. Sol. RRL. 2020;4(3):1–8. doi: 10.1002/solr.201900505. DOI