Full length article Potential effect of CuInS 2 /ZnS core-shell quantum dots on P3HT/PEDOT: PSS heterostructure based solar cell Shikha Jindal, S.M. Giripunje ⇑ Department of Physics, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra, India article info Article history: Received 26 September 2017 Received in revised form 20 December 2017 Accepted 16 January 2018 Keywords: Quantum dots CuInS 2 /ZnS Current density – voltage UPS abstract Nanostructured quantum dots (QDs) are quite promising in the solar cell application due to quantum confinement effect. QDs possess multiple exciton generation and large surface area. The environment friendly CuInS 2 /ZnS core-shell QDs were prepared by solvothermal method. Thus, the 3 nm average sized CuInS 2 /ZnS QDs were employed in the bulk heterojunction device and the active blend layer consisting of the P3HT and CuInS 2 /ZnS QDs was investigated. The energy level information of CuInS 2 /ZnS QDs as an electron acceptor was explored by ultra violet photoelectron spectroscopy. Bulk heterojunction hybrid device of ITO/PEDOT:PSS/P3HT: (CuInS 2 /ZnS QDs)/ZnO/Ag was designed by spin coating approach and its electrical characterization was investigated by solar simulator. Current density – voltage characteris- tics shows the enhancement in power conversion efficiency with increasing concentration of CuInS 2 /ZnS QDs in bulk heterojunction device. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Nanotechnology plays a vital role in the field of electronics owing to its inimitable optical and electronic properties. QDs are renowned because of their large surface area to volume ratio, increased activity, unique size dependent optical and electronic properties as compared to bulk material. It exhibits discrete energy levels and tunable band gap due to the quantum confinement effect [1]. These properties can be exploited and utilized for various applications including gas sensing [2], bio imaging [3], sensors [4], solar cells [5], light emitting diodes [6] and photo catalysis [7]. Semiconductor quantum dots attained high surface area, multiple exciton generation and it can tune optical band gap by changing the size and composition of quantum dots [8,9]. From the past dec- ades, most of the toxic semiconductor materials like CdS, CdSe and CdTe were investigated and used in various applications. These materials manifest optimal performance in electronic devices. Inspite of the distinctive performance, these materials cannot be persistent for environmental benign applications as its toxicity causes drastic effects in the environment. Thus, many researcher groups emphasized the non-toxic materials to conquered the haz- ardous effects using environmental benign materials such as SnS [10], ZnS [11], CuS [12], TiO 2 [13], ZnO [14], CuInS 2 [15,16], CuInSe 2 [17] and AgInS 2 [18] for optoelectronic devices. The direct band gap of 1.5 eV and high absorption coefficient of CuInS 2 , ascribes it a most pertinent semiconductor for device applications. Inher- ently, the shell material had overcoated around the surface of semiconductor material to enhance the stability. Thus, the various core-shell semiconductors such as SnS/In 2 S 3 [19], CdSe/CdS/ZnS [20], CdTe/ZnS [21] and SnO 2 /SnS 2 [22] have been reported in the literature. Among these, ZnS is a plausible shell material due to its non-toxicity and wide band gap to localize charge carriers inside the core material. Besides, ZnS is appropriate material for CuInS 2 core owe to the similar crystal structures of both the semi- conductors with the small lattice mismatch of about 2.2% [23]. Consequently, the CuInS 2 /ZnS core-shell QDs is the best semicon- ductor material for solar cell applications. CuInS 2 /ZnS QDs had been fabricated by hybrid flow reactor [24], solvothermal process [25], one pot synthesis [26]. The hybrid solar cell devices consisting of organic polymers and inorganic QDs had been investigated by many researchers owing to the interesting properties of polymers such as possible recyclabil- ity and applicability as sustainable materials and properties of inorganic QDs as high dielectric constant, high absorption coeffi- cient and high photoconductivity [27]. In addition, bulk hetero- junction type hybrid device has many advantages of phase segregation, continuous network between donor acceptor material enhances the absorption, dissociation and fast exciton transfer at high rate [28,29]. Hybrid solar cell of P3HT:CdSe/ZnS along with SWCNT had achieved the conversion efficiency of 5.4% [30]. More- over, bulk heterojunction solar cell based on HgTe:PSBTBT polymer https://doi.org/10.1016/j.optlastec.2018.01.047 0030-3992/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: smgiripunje@phy.vnit.ac.in (S.M. Giripunje). Optics and Laser Technology 103 (2018) 212–218 Contents lists available at ScienceDirect Optics and Laser Technology journal homepage: www.elsevier.com/locate/optlastec