CdS-phenanthroline derivative hybrid cathode interlayers for high performance inverted organic solar cellsElectronic supplementary information (ESI) available: Details of the XPS spectra of CdS and CdS-BCP, J-V characteristics of OSCs based on various solvents with different concentrations, AFM height images of CdS-BCP with different solvents, EQE, absorption spectra, characteristic curves of electron-only devices, AFM height images of PTB7 : PC71BM and UPS spectra. See DOI: 10.1039/c5ta06952a

Phenanthroline based organic semiconductors (BCP, Bphen, Mphen, and Phen) are used to hybrid with CdS as cathode interlayers in inverted organic solar cells (OSCs). We observed that selecting the polar solvent and hydrophobic interlayers with a diphenyl group could improve the performance of the organic photovoltaic devices. The modification to CdS can effectively improve its electron mobility, film morphology, interfacial contact, and energy level alignment, which finally leads to a significant enhancement of device performance. Through incorporating the CdS-P hybrids (CdS-BCP, CdS-Bphen, CdS-Mphen, and CdS-Phen) as cathode buffer layers, the device PCE (PTB7 : PC 71 BM as the active layer) is greatly improved from 3.09% to 8.36, 7.84, 6.69, and 6.57%, respectively, compared with devices fabricated on the pristine CdS interlayer. These results indicate that the common inorganic semiconductor like CdS can be modified using some organic semiconductors to produce general applicable electron transport layers applied in OSCs. Our work puts forward new insights for the development of new interface modification materials and fabrication of high efficiency devices. High performance inverted OSCs were achieved by using CdS-phenanthroline derivative hybrids as electron transporting layers through thermal decomposition.