Measurement of charge carrier recombination rates in planar hybrid CdS/poly3-octylthiophene solar cells

• Published in: Solar energy 2012-04, Vol.86 (4), p.1004-1009
• Main Authors: Cortina, Hugo, Pineda, Edwin, Hu, Hailin
• Format: Article
• Language: English
• Subjects: Applied sciences; Cadmium sulfide; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; Humidity; Natural energy; Organic solar cells; Photoelectric conversion; Photovoltaic cells; Photovoltaic conversion; Poly3-octylthiophene; Solar cells. Photoelectrochemical cells; Solar energy; Thin films; Time-of-flight method; Transient photoconductivity; Transient photovoltage
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2011.06.003

► Transient photoconductance, time-of-flight, transient photovoltage were discussed. ► Charge recombination rates (τ) in CdS thin films, P3OT and CdS/P3OT were estimated. ► Thinner P3OT film leads to a larger τ value at CdS/P3OT interface. ► The ambient oxygen may increase the charge recombination center density in P3OT. Hybrid bilayer solar cells have been prepared by chemical bath deposition of cadmium sulfide (CdS) thin films on conductive glass and drop cast poly3-octylthiophene (P3OT) solution on top of CdS free surface. Gold contact on P3OT film was thermally evaporated. Transient photoconductance decay method was implemented to determine the charge carrier recombination times in CdS films. The same parameter in P3OT films was estimated by time-of-flight technique. Charge recombination processes in CdS/P3OT interface were studied by transient photovoltage method. The relation between the photovoltaic performance of hybrid cells and charge recombination times at CdS/P3OT interface was analyzed as a function of P3OT film thickness. It is suggested that the ambient oxygen or humidity may originate the increased charge recombination center density in thinner P3OT films and, as a result, deteriorate the short-circuit current density and open-circuit voltage values of the corresponding hybrid cells.