pubs.acs.org/NanoLett
High-Performance Nanostructured Inorganic-Organic Heterojunction Solar Cells Jeong Ah Chang,†,§ Jae Hui Rhee,†,§ Sang Hyuk Im,† Yong Hui Lee,† Hi-jung Kim,† Sang Il Seok,*,† Md. K. Nazeeruddin,‡ and Michael Gratzel‡ †
KRICT-EPFL Global Research Laboratory, Advanced Materials Division, Korea Research Institute of Chemical Technology, 19 Sinseongno, Yuseong, Daejeon 305-600, Republic of Korea, and ‡ Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Science, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland ABSTRACT We report all solid-state nanostructured inorganic-organic heterojunction solar cells fabricated by depositing Sb2S3 and poly(3-hexylthiophene) (P3HT) on the surface of a mesoporous TiO2 layer, where Sb2S3 acts as an absorbing semiconductor and P3HT acts as both a hole conductor and light absorber. These inorganic-organic light harvesters perform remarkably well with a maximum incident-photon-to-current efficiency (IPCE) of 80% and power conversion efficiency of 5.13% under air-mass 1.5 global (AM 1.5G) illumination with the intensity of 100 mW cm-2. These devices are highly stable under room light in air, even without encapsulation. The present findings offer novel directions for achieving high-efficiency solid-state solar cells by hybridization of inorganic-organic light harvesters and hole transporters. KEYWORDS Sb2S3, P3HT, inorganic-organic heterojunction, solar cells
A
lthough single-crystalline Si-based solar cells are successfully used to harvest solar energy, inexpensive production of photovoltaic (PV) devices at a cost comparable to the energy production cost of fossil fuels has become a critical issue to meet the global energy crisis. Among the several novel PV devices, dye-sensitized solar cells (DSSCs)1-3 and organic solar cells (OSCs),4,5 which exhibit efficiencies of 11.53 and 6.77%,5 respectively, are considered to represent low-cost alternatives to conventional inorganic devices. However, liquid-electrolyte-based DSSCs suffer from the problem of solvent leakage, and OSCs have a significantly short lifetime. To overcome this disadvantage, solid-state organic hole-transporting materials spiro-MeOTAD [2,22′,7,77′-tetrkis (N,N-di-p-methoxyphenylamine)9,99′-spirobi fluorine] have been investigated, which gave 5% certified efficency.3,6-8 Inorganic p-type materials such as CuI9 and CuSCN,10,11 conducting polymers such as poly(3hexylthiophene) (P3HT)12 and poly(3,4-ethylenedioxythiophene) PEDOT,13 polyaniline,14 polydiacetyllene,15 and so forth have also been studied as materials for fabricating solid hole-transporter. For the fabrication of sensitized solar cells, the process of semiconductor sensitization offers several advantages over the use of ruthenium/organic sensitizers: excellent optical properties, which can be tuned by controlling the semiconductor dimensions,16 a high extinction coefficient,17 and a large intrinsic dipole moment.18 Because of their
excellent light-harvesting property, inorganic semiconductors are ideal sensitizers for solar cells.16 Furthermore, there is evidence of multiple exciton phenomena in quantumconfined inorganic semiconductors (quantum dots, QDs).19 Thus, solar cells based on QDs would bring new hope to make a breakthrough for the next-generation solar devices. In recent years, several groups,20-22 including ours,23-25 have reported inorganic semiconductors-sensitized solar cells. Unfortunately, however, the efficiency of these solar cells is still low (
