What is a deep defect? Combining Shockley-Read-Hall statistics with multiphonon recombination theory

Das, Basita; Aguilera, Irene; Rau, Uwe; Kirchartz, Thomas

doi:10.1103/physrevmaterials.4.024602

Cited by 49 publications

(66 citation statements)

References 61 publications

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“…However, when the NR center (the supertrap) is activated, it collects and recombines non‐radiatively a large fraction of charge carriers generated within the diffusion length from the NR center (Figure 1d), which leads to PL intensity and a lifetime correlated decrease observed experimentally (see Supporting Information). [ 21 ] PL intensity drop is determined by the fraction of charge carriers collected by the NR center which is dependent on: effective diffusion length of electron and holes (including energy transfer and photon reabsorption/recycling terms, [ 56,57 ] capturing cross‐section, [ 58,59 ] and the NR recombination rate of the NR center itself. The cartoon in Figure 1d shows the case of the diffusion‐limited quenching.…”

Section: Discussionmentioning

confidence: 99%

Lack of Photon Antibunching Supports Supertrap Model of Photoluminescence Blinking in Perovskite Sub‐Micrometer Crystals

Eremchev

Tarasevich

et al. 2020

Advanced Optical Materials

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Antibunching effect is typically observed in individual systems possessing photoluminescence (PL) blinking and vice versa. Contrary to this common perception, absence of antibunching in strongly blinking methyl ammonium led tri‐iodide (MAPbI3) perovskite crystals of sizes from tens to hundreds of nanometers regardless of the excitation power density is observed. Antibunching effect does not appear even when photon statistics are analyzed for bright and intermediate PL intensity levels independently. This shows that there is no directional energy funneling and accumulation of charge carriers in the small local regions in MAPbI3 crystals where an Auger recombination can potentially suppress the simultaneous emission of two photons. This result allows for the exclusion of the PL blinking mechanism based on the idea of emitting sites previously hypothesized for perovskites. Therefore, the model of PL blinking in perovskite crystals based on the presence of a metastable non‐radiative recombination center (the supertrap) is the only one proposed so far which explains blinking without conflicting with the absence of photon correlations.

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Section: Discussionmentioning

confidence: 99%

Lack of Photon Antibunching Supports Supertrap Model of Photoluminescence Blinking in Perovskite Sub‐Micrometer Crystals

Eremchev

Tarasevich

et al. 2020

Advanced Optical Materials

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“…For the V Cd 1– ⇄ V Cd 0 transitions, however, the behavior is drastically different to that predicted by a simple quantum defect model. 63 First, hole capture is more rapid than expected, due to the ability of V Cd 1– to transition to the metastable V Cd,Bipolaron 0 configuration, before relaxing to the V Cd,Te Dimer 0 ground state. Second, despite the (−/0) Te Dimer trap level lying over 1 eV below the CBM ( Figure 4 ), typically implying slow electron capture, we in fact find a giant electron capture coefficient.…”

Section: Trap-mediated Recombinationmentioning

confidence: 93%

Rapid Recombination by Cadmium Vacancies in CdTe

2021

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CdTe is currently the largest thin-film photovoltaic technology. Non-radiative electron–hole recombination reduces the solar conversion efficiency from an ideal value of 32% to a current champion performance of 22%. The cadmium vacancy (V Cd ) is a prominent acceptor species in p -type CdTe; however, debate continues regarding its structural and electronic behavior. Using ab initio defect techniques, we calculate a negative-U double-acceptor level for V Cd , while reproducing the V Cd 1– hole–polaron, reconciling theoretical predictions with experimental observations. We find the cadmium vacancy facilitates rapid charge-carrier recombination, reducing maximum power-conversion efficiency by over 5% for untreated CdTe—a consequence of tellurium dimerization, metastable structural arrangements, and anharmonic potential energy surfaces for carrier capture.

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“…[7,9] If a trap level is close to the conduction band, it will be easy for electron to get trapped (large cross-section for electron trapping), however, it will be very difficult for this electron to recombine with a free hole (or for a hole to be trapped by the negatively charged defect) because of a very large energy distance to the valence band. [9,11] Therefore, the hole capture crosssection will be very small, making the recombination very slow (microseconds, milliseconds). Such a trap can be easily filled and will not cause any problems if the concentration of charges is high enough.…”

Section: How Can Diffusion Of Excitations Make Nonradiative Recombinamentioning

confidence: 99%

“…The logic here is simple: the larger the energy gap between the two states, the more difficult is the transition [7,9] . If a trap level is close to the conduction band, it will be easy for electron to get trapped (large cross‐section for electron trapping), however, it will be very difficult for this electron to recombine with a free hole (or for a hole to be trapped by the negatively charged defect) because of a very large energy distance to the valence band [9,11] . Therefore, the hole capture cross‐section will be very small, making the recombination very slow (microseconds, milliseconds).…”

Section: How Can Diffusion Of Excitations Make Nonradiative Recombinamentioning

confidence: 99%

Small Number of Defects per Nanostructure Leads to “Digital” Quenching of Photoluminescence: The Case of Metal Halide Perovskites

Scheblykin

2020

Advanced Energy Materials

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in devices. Solution processability implies the presence of a high concentration of crystal defects, making many new materials inefficient emitters and poor conductors. The primary energy loss channel is the nonradiative (NR) recombination of excited electrons and holes assisted by charge trapping. [2] Rationalizing the charge recombination mechanisms, the properties of the NR recombination centers and their origin are crucially important for technological applications. The case of MHPs is very peculiar and seems contradictory. Low temperature solution processing with very fast crystallization under the condition of kinetic competition between many processes should lead to high concentrations of crystal defects. However, somehow it is not a severe problem for device efficiency. [2-5] Here it is important to realize that not every defect leads to NR recombination, and even if some do, their efficiency can vary

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What is a deep defect? Combining Shockley-Read-Hall statistics with multiphonon recombination theory

Cited by 49 publications

References 61 publications

Lack of Photon Antibunching Supports Supertrap Model of Photoluminescence Blinking in Perovskite Sub‐Micrometer Crystals

Lack of Photon Antibunching Supports Supertrap Model of Photoluminescence Blinking in Perovskite Sub‐Micrometer Crystals

Rapid Recombination by Cadmium Vacancies in CdTe

Small Number of Defects per Nanostructure Leads to “Digital” Quenching of Photoluminescence: The Case of Metal Halide Perovskites

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