Ultrafast Exciton‐to‐Polaron Conversion in Densely Packed Small Organic Semiconducting Molecules

Abstract

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Simple donor-acceptor molecule with long exciton diffusion length for organic photovoltaics

“…Low VOC losses were also previously found in linear [70] and star-shaped [54] TPA-DCV-based molecules. Partially, the low VOC loss in TPA-T-DCV-Ph:C70 is explained by the low energy disorder [71] of TPA-T-DCV-Ph; however, the share of disorder-induced VOC losses to the total losses are typically only ~0.1 V [72].…”

“…3a, 96 nm neat curve). This value is unexpectedly long for a solid film of push-pull material (where the typical lifetimes are less than 1 ns) [37,[52][53][54][55] and suggests the potential for long exciton diffusion in the vacuum-deposited TPA-T-DCV-Ph.…”

Orientation dependent molecular electrostatics drives efficient charge generation in homojunction organic solar cells

“…Efficient free charge generation in pristine organic semiconductors without intermolecular CT character has been rarely reported to date (unless very high photon energies are used 37 ) due to the strong binding energy of excitons in such materials (typically estimated as several hundreds of meV). Only a few spectroscopic studies have suggested ultrafast photogeneration of free charge carriers in pristine organic small molecule films, with these reporting only low EQEs of less than 10% and more often less than 1% 37 – 40 . For example, Keiderling et al reported charge generation in pristine PCBM thin films.…”

Polaron and Spin Dynamics in Organic–Inorganic Lead Halide Perovskite Nanocrystals

“…As manifested from Equation (), the substantial difference between ε ∞ = 6.9 [ 52 ] and ε s = 49.4 [ 53 ] results in strong carrier–phonon interactions in FAPbI 3 leading to polaron formation, which reduces the Coulomb interaction related scattering phenomena. [ 9,10,25–28 ] This effect results in the protection of bandedge carriers for ≈30 ps. The hallmark of such long‐lived bandedge carriers in Figure 2c without decay for nearly 30 ps and reduced spectral redshift revealed in Figure 2b can thus be attributed to the polaron induced screening of the many‐body Coulomb potential.…”

“…[ 9,10,25–27 ] Such behavior of carrier protection by polarons (carriers dressed by the long‐range polarized lattice deformation) has already been demonstrated in OILHP single crystals. [ 9,10,25–28 ] The formation of polarons in OILHP is the direct outcome of the intrinsic softness and the polarizability of Pb‐X lattice. [ 10,26,29,30 ] Even though photophysics and carrier dynamics in OILHP single crystals have been intensively studied, such investigations on confined NCs are rather limited.…”