Enhancement of Photoresponse Properties of Conjugated Polymers/Inorganic Semiconductor Nanocomposites by Internal Micro-Magnetic Field

Graphical Hybrid materials : The internal micro-magnetic field (IMMF) effect in Fe 3 O 4 @PANI-CdS photoelectric active hybrid nanocomposites was found to improve their power conversion efficiencies ( PCE ) by increasing the number of singlet polaron pairs through field-dependent intersystem crossing (ISC). The PCE of as-prepared nanocomposites was improved from 1.135 to 3.563 % with changes in IMMF from 0 to 1.2×10 −3 emu g −1 (see figure). In this paper, the effect of the internal micro-magnetic field (IMMF) on the photocurrent property of conjugated polymer/inorganic semiconductor nanocomposites is reported and analyzed. By using the redox reaction, magnetic Fe 3 O 4 nanoparticles were coated on the surface of highly active nanorods of conjugated polyaniline (PANI), forming an internal micro-magnetic electron donor (i.e., Fe 3 O 4 @PANI). After subsequent incorporation of CdS nanoparticles (serving as electron acceptors), the power conversion efficiency ( PCE ) of the system (Fe 3 O 4 @PANI-CdS) was found to be as high as 3.563 %, contrasting sharply with the value (1.135 %) of the hybrid without Fe 3 O 4 (PANI-CdS). This obvious enhancement originated from the fact that the IMMF increased the number of singlet polaron pairs through field-dependent intersystem crossing (ISC), giving a positive contribution to the photocurrent generation. Additionally, the dependence of the photocurrent on the remnant magnetization of the Fe 3 O 4 @PANI-CdS nanocomposites was investigated. A percolation behavior was observed, which was due to the appearance of interpenetrating networks consisting of donor and acceptor phases, leading to the recombination of charge carriers through trapping. The outcomes of the present work might help to produce a new family of conjugated organic/inorganic semiconductor nanocomposites with designed optoelectronic performances.