Improving the performance of inorganic-organic hybrid photovoltaic devices by uniform ordering of ZnO nanorods and near-atmospheric pressure nitrogen plasma treatment

Abstract

Efficiency enhancement of organic photovoltaic devices using a Sm:Al compound electrode Appl. Phys. Lett. 102, 073301 (2013) Efficiency enhancement of organic photovoltaic devices using a Sm:Al compound electrode APL: Org. Electron. Photonics 6, 33 (2013) Electronic and interface properties of polyfluorene films on GaN for hybrid optoelectronic applications APL: Org. Electron. Photonics 6, 29 (2013) Electronic and interface properties of polyfluorene films on GaN for hybrid optoelectronic applications Appl. Phys. Lett. 102, 063303 (2013) A trilayer architecture for polymer photoconductors Appl. Phys. Lett. 102, 053304 (2013) Additional information on J. Appl. Phys. We investigated the performance of hybrid photovoltaic devices composed of ZnO and poly (3-hexylthiophene) (P3HT). The uniform ordering of ZnO nanorods (NRs) and nitrogen plasma treatment at near-atmospheric pressure offer advantages in modifying the ZnO NR surface. Uniform ordering of the ZnO NRs promoted the effective infiltration of P3HT, increasing the donor-acceptor interface area, which is directly related to short-circuit current density (J SC ). Nearatmospheric pressure treatment compensated carriers to form a highly resistant interlayer at the ZnO surface, which reduced carrier recombination and, as a result, increased the open circuit voltage (V OC ). Combining these two approaches achieved five-fold increase in J SC compared to that of the planar heterojunction, while the V OC was increased up to 0.71 V.

Surface Structure Modification of ZnO and the Impact on Electronic Properties

“… i) Doping : doping of the ZnO bulk will also change the surface characteristics of the material; alternatively, surface doping may be carried out by depositing a thin layer of doped ZnO material on top of an undoped ZnO thin‐film, or by surface treatments such as UV–ozone or plasma exposure . A comprehensive overview of ZnO doping is given in the excellent review by Özgür et al Nominally, elements such as Al, Ga, In, and Cl may be used for n‐type doping, whereas Li, Na, N, P, and As are used for p‐type doping; however, the actual behavior of dopants can be highly variable and is discussed in more detail in the relevant sections in this review.…”

“…Doping of ZnO can also be used to control surface defects and may be achieved by using treatments which only affect the near‐surface region of the oxide film: UV–ozone treatment, for example, has been thought to change the interfacial dipole at the ZnO surface, although this treatment was observed to reduce the overall hPV device performance . Surface doping with nitrogen has been undertaken by different methods: in the report by Oh et al, this was achieved by using a near‐atmospheric‐pressure nitrogen‐plasma treatment on a well‐ordered ZnO NR array, leading to implantation of the N 3− ion in the surface . This treatment created a more‐resistive ZnO surface, and substantial gains in V oc were realized (0.30 V to 0.71 V), which were attributed to a reduction in leakage current through defect passivation; however, this was accompanied by a 12% reduction in J sc .…”

Crystallographic polarity effect of ZnO on thin film growth of pentacene

“…2,3) Among of inorganic materials, ZnO is a promising candidate for an inorganic semiconductor in an organic= inorganic structure because of its characteristics such as excellent transparency, high electrical conductivity, and potential for use in a crystal nanoassembly. 4) Furthermore, ZnO is a wide-band-gap (3.37 eV) semiconductor that exhibits good optoelectronic properties in the ultraviolet region. 5,6) Excitons related to charge transfer across the interface in organic=ZnO systems have been observed.…”

Photoelectron spectroscopic study on monolayer pentacene thin-film/polar ZnO single-crystal hybrid interface

“…2,3) Among a number of inorganic materials, ZnO is a promising candidate for an inorganic semiconductor in an organic=inorganic structure because of its characteristics such as excellent transparency, high electrical conductivity, and potential use in a crystal nanoassembly. 4) Furthermore, ZnO is a semiconductor with a wide band gap (3.37 eV) that exhibits good optoelectronic properties in the ultraviolet region. 5,6) Excitons related to charge transfer across the interface in organic=ZnO systems have been observed.…”