Solid-state infrared-to-visible upconversion sensitized by colloidal nanocrystals

Wu, Mengfei; Congreve, Daniel N.; Wilson, Mark W.; Jean, Joel; Geva, Nadav; Welborn, Matthew; Voorhis, Troy Van; Bulović, Vladimir; Bawendi, Moungi G.; Baldo, Marc A.

doi:10.1038/nphoton.2015.226

Cited by 441 publications

(634 citation statements)

References 27 publications

Supporting

Mentioning

597

Contrasting

Unclassified

Order By: Relevance

“…The highest Φ TTA-UC and η TTA-UC for rubrene are 23% and 70%, respectively (For DPA and perylene, the efficiencies are slightly lower). To the best of our knowledge, these values are higher than that of any solid-state TTA-upconverters reported to date [9][10][11][12][13][14]19] and are comparable to some of the best TTA-UC efficiencies observed in solutionphase systems. [9][10][11][12]18] A summary of the efficiencies of solution systems [17,18,[31][32][33] is shown in Table S2 (Supporting Information).…”

Section: Doi: 101002/adma201605987mentioning

confidence: 43%

“…This reaction obeys spin conservation and is referred to as triplet fusion or TTA-UC in the upconversion literature. [9][10][11][12][13][14] In Stage III, the triplet-fusion-generated singlet recombines and produces delayed emission.…”

Section: Doi: 101002/adma201605987mentioning

confidence: 99%

“…[9][10][11][12]18] A summary of the efficiencies of solution systems [17,18,[31][32][33] is shown in Table S2 (Supporting Information). Comparisons of our devices with other solid-state TTA-UC systems [13,14,19,31,34] and other TTA-enhanced OLEDs [7,8,[35][36][37] are presented in Tables S3 and S4 (Supporting Information), respectively. The remarkably high TTA-UC efficiencies in our best devices suggest that only singlets are formed during the TTA process.…”

Section: Doi: 101002/adma201605987mentioning

confidence: 99%

“…[6][7][8] At the same time, photon upconversion through TTA has been widely considered for next-generation photovoltaic applications. [9][10][11][12][13][14] Effective upconverters have been demonstrated using combinations of a triplet sensitizer such as platinum octaethylporphyrin (PtOEP) [3] and a triplet acceptor/annihilator such as 9,10-diphenylanthracene (DPA), [15] perylene, [16] or rubrene.[17] TTA-upconversion (TTA-UC) quantum yield (ratio of upconverted photons to absorbed photons) of 30% was observed in solution phase. [18] This suggests that the intrinsic efficiency of the TTA-UC reaction (i.e., the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

et al. 2017

View full text Add to dashboard Cite

probability of a triplet pair forming a singlet) in solution is >60%, much higher than the spin-statistical prediction of 25% (one pair of triplets collides to form one of the four states: one singlet S 1 and three triplets T 1 , assuming higher triplet and quintet states are inaccessible). Practical application of solar energy conversion requires the TTA-UC material to be in solid state rather than in solution phase. However, the TTA-UC quantum yield of solidstate systems remains low, typically below 5%, [10] and is moderately high (about 10%) in only one example. [19] To achieve high efficiencies, high excitation intensities (200 mW cm −2 or above) are commonly required. These imply that in solid state, the experimentally observed reaction efficiency of TTA-UC was up to about 20%, below the 25% spin-statistical limit.To achieve highly efficient triplet fusion (TTA-UC) in OLEDs and other TTA upconverters, we consider four criteria for the selection of emitters: (1) high fluorescence quantum yield, (2) short singlet lifetime, (3) long triplet lifetime, and (4) the energy of two triplet excitons, 2E(T 1 ) lies slightly above that of the singlet exciton, E(S 1 ), but below the second triplet state, E(T 2 ) (and also the energies of any spin-quintet states) (E(S 1 ) ≲ 2E(T 1 ) < E(T 2 )). The first and second criteria are prerequisites for efficient fluorescence. The third criterion is essential for the accumulation of a sufficiently high triplet population density required for rapid triplet-triplet collision processes. The fourth criterion ensures that higher-lying triplet or quintet states do not provide loss channels. The spin states of the triplet excitons give in principle nine spin configurations for the interacting triplet exciton pair, five associated with a quintet, three with a triplet, and one with the singlet state. It is generally considered that the quintet is always higher in energy than the initial triplet pair, so is neglected. If there are no energetically accessible higher-lying triplet states at E(T 2 ), we expect only the S 1 and T 1 excitons to form. Triplets produced from this reaction can be recycled and participate in a further fusion reaction. [7] The basic working principle of a triplet fusion LED (FuLED) is illustrated in Figure 1a. The initial stage (Stage I) of the device operation includes charge injection and exciton formation. Exciton formation on the emissive molecules may occur directly or indirectly through an additional exciton transfer step from a host material. If a host material is present, the S 1 and T 1 of the host are required to be higher than that of the emitter to allow efficient host-emitter energy transfer and to ensure long triplet lifetime of the emitter (Criterion 3 discussed above). The 25% singlet population can be converted to light emission (and nonradiative losses) from the singlet channel immediately, resulting in prompt electroluminescence (EL). The 75% triplet excitons remain nonemissive, but the population of triplets is When an organic light-emitting dio...

show abstract

Section: Doi: 101002/adma201605987mentioning

confidence: 43%

Section: Doi: 101002/adma201605987mentioning

confidence: 99%

Section: Doi: 101002/adma201605987mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Among the most promising concepts to supress loss processes associated with incomplete absorption are photon up-conversion mechanisms where low energy photons below the band gap are recovered for solar cell operation [8,9]. As this concept, however, is not within the main focus of this article, we refer the interested reader to other reviews addressing the topic in the literature [10].…”

Section: Introductionmentioning

confidence: 99%

Multiple exciton generation in quantum dot-based solar cells

et al. 2017

View full text Add to dashboard Cite

Multiple exciton generation (MEG) in quantumconfined semiconductors is the process by which multiple bound charge-carrier pairs are generated after absorption of a single high-energy photon. Such charge-carrier multiplication effects have been highlighted as particularly beneficial for solar cells where they have the potential to increase the photocurrent significantly. Indeed, recent research efforts have proved that more than one chargecarrier pair per incident solar photon can be extracted in photovoltaic devices incorporating quantum-confined semiconductors. While these proof-of-concept applications underline the potential of MEG in solar cells, the impact of the carrier multiplication effect on the device performance remains rather low. This review covers recent advancements in the understanding and application of MEG as a photocurrent-enhancing mechanism in quantum dot-based photovoltaics.

show abstract

Triplet Energy Transfer from PbS(Se) Nanocrystals to Rubrene: the Relationship between the Upconversion Quantum Yield and Size

Mahboub

Maghsoudiganjeh

Pham

et al. 2016

Adv Funct Materials

100

View full text Add to dashboard Cite

Photon upconversion has attracted enormous attention due to its wide range of applications in biological imaging, photocatalysis, and especially photovoltaics. Here, the effect of quantum confinement on the efficiency of Dexter energy transfer from PbS and PbSe nanocrystals (NCs) to a rubrene acceptor is studied. A series of experiments exploring the relationship between NC size and the upconversion quantum yield (QY) in this hybrid platform show that energy transfer occurs in the Marcus normal regime. By decreasing the NC diameter from 3.5 to 2.9 nm for PbS and from 3.2 to 2.5 nm for PbSe, the relative upconversion QY is enhanced about 700 and 250‐fold respectively. In addition, the dynamic Stern–Volmer constant (KSV) for the quenching of PbSe NCs by rubrene increases approximately fivefold with a decrease in NC diameter from 3.2 to 2.5 nm to a value of 200 m−1. This work shows that high quality, well‐passivated, small NCs are critical for efficient triplet energy transfer to molecular acceptors.

show abstract

Solid-state infrared-to-visible upconversion sensitized by colloidal nanocrystals

Cited by 441 publications

References 27 publications

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

Multiple exciton generation in quantum dot-based solar cells

Triplet Energy Transfer from PbS(Se) Nanocrystals to Rubrene: the Relationship between the Upconversion Quantum Yield and Size

Contact Info

Product

Resources

About