Emergence of New Materials for Exploiting Highly Efficient Carrier Multiplication in Photovoltaics

In conventional solar cell semiconductor materials (predominantlySi)photons with energy higher than the band gap initially generate hot electrons and holes, which subsequently cool down to the band edge by phonon emission. Due to the latter process,the energy of the charge carriers in excess of the band gap is lost as heat and does not...

Generating Triplets in Organic Semiconductor Tetracene upon Photoexcitation of Transition Metal Dichalcogenide ReS₂

We studied the dynamics of transfer of photoexcited electronic states in a bilayer of the two-dimensional transition metal dichalcogenide ReS2 and tetracene, with the aim to produce triplets in the latter. This material combination was used as the band gap of ReS2 (1.5 eV) is slightly larger than the triplet energy of tetracene (1.25 eV)....

Unraveling the Photophysics of Liquid-Phase Exfoliated Two-Dimensional ReS₂Nanoflakes

Few-layered transition-metal dichalcogenides (TMDs) are increasingly popular materials for optoelectronics and catalysis. Among the various types of TMDs available today, rhenium chalcogenides (ReX2) stand out due to their remarkable electronic structure, such as the occurrence of anisotropic excitons and potential direct band gap behavior...

Effects of the Structure and Temperature on the Nature of Excitons in the Mo_0.6W_0.4S₂Alloy

We studied the nature of excitons in the transition metal dichalcogenide alloy Mo0.6W0.4S2 compared to pure MoS2 and WS2 grown by atomic layer deposition (ALD). For this, optical absorption/transmission spectroscopy and time-dependent density functional theory (TDDFT) were used. The effects of temperature on A and B exciton peak energies and...

Efficient Carrier Multiplication in Low Band Gap Mixed Sn/Pb Halide Perovskites

Carrier multiplication (CM) generates multiple electron-hole pairs in a semiconductor from a single absorbed photon with energy exceeding twice the band gap. Thus, CM provides a promising way to circumvent the Shockley-Queisser limit of solar cells. The ideal material for CM should have significant overlap with the solar spectrum and should...

Change in Tetracene Polymorphism Facilitates Triplet Transfer in Singlet Fission-Sensitized Silicon Solar Cells

Singlet fission in tetracene generates two triplet excitons per absorbed photon. If these triplet excitons can be effectively transferred into silicon (Si), then additional photocurrent can be generated from photons above the bandgap of Si. This could alleviate the thermalization loss and increase the efficiency of conventional Si solar cells...

Structure, transport and photoconductance of PbS quantum dot monolayers functionalized with a copper phthalocyanine derivative

We simultaneously surface-functionalize PbS nanocrystals with Cu 4,4′,4′′,4′′′-tetraaminophthalocyanine and assemble this hybrid material into macroscopic monolayers. Electron microscopy and X-ray scattering reveal a granular mesocrystalline structure with strong coherence between the atomic lattice and the superlattice of nanocrystals within...