Qiwei Jiang

Core/shell-shaped CdSe/PbS nanotetrapods for efficient organic–inorganic hybrid solar cells

Core/shell-shaped CdSe/PbS nanotetrapod (NT), a novel nanostructure, has been synthesized and incorporated as an electron acceptor in organic–inorganic hybrid bulk-heterojunction (HBH) solar cells with poly(3-hexylthiophene) (P3HT) acting as an electron donor. The composite NT shows an homogeneous decoration of 4 nm PbS quantum dots on the CdSe NT surface, forming an inorganic heterojunction with a type-II band alignment. Compared to pure CdSe NT, the core/shell-shaped NT demonstrates an improved performance on splitting photogenerated exciton in P3HT. The charge reverse transfer (leakage or recombination) at the heterojunction interface is suppressed due to a potential barrier that is as high as 0.5 eV for CdSe/PbS NT. Furthermore, charge transport and collection are also enhanced through the spatially isolated charge channels of P3HT (for holes) and the CdSe core (for electrons). The efficient exciton dissociation and charge collection greatly contribute to the photovoltaic performance improvement. Compared with the P3HT:CdSe hybrid solar cell, a remarkable efficiency enhancement of 76% is achieved by incorporating the P3HT:CdSe/PbS hybrid with a donor–acceptor mass ratio of 1 : 6.

Nanotetrapods: quantum dot hybrid for bulk heterojunction solar cells

Hybrid thin film solar cell based on all-inorganic nanoparticles is a new member in the family of photovoltaic devices. In this work, a novel and performance-efficient inorganic hybrid nanostructure with continuous charge transportation and collection channels is demonstrated by introducing CdTe nanotetropods (NTs) and CdSe quantum dots (QDs). Hybrid morphology is characterized, demonstrating an interpenetration and compacted contact of NTs and QDs. Electrical measurements show enhanced charge transfer at the hybrid bulk heterojunction interface of NTs and QDs after ligand exchange which accordingly improves the performance of solar cells. Photovoltaic and light response tests exhibit a combined optic-electric contribution from both CdTe NTs and CdSe QDs through a formation of interpercolation in morphology as well as a type II energy level distribution. The NT and QD hybrid bulk heterojunction is applicable and promising in other highly efficient photovoltaic materials such as PbS QDs.