Nanophotonics of heterostructures is an important step in solving the problem of environmental safety of transport infrastructure

. A safe transportation ecosystem encompasses both the passenger and attendant populations as well as the abiotic infrastructure that surrounds them. Solar cells generating electricity are one of the most promising options for building a long-term energy base for the transportation ecosystem, given the trends related to the increasing role of green energy in various industries. The physical foundations for the practical implementation of solar cells are being laid by research in nanophotonics. The role of model representations based on FRET and reverse transport mechanisms are examined in the example of luminescence photodynamics of a heterostructure representing isolated films of CdSe/ZnS-TOPO quantum dots containing InP/InAsP/InP nanowires. The studies performed in this work suggest practical ways to increase the luminescence yield of heterostructures using "interfacial technologies" in core-shell structures


Introduction
Typically, an ecosystem includes a biological fragment as well as the physical and chemical factors that make up its abiotic environment. Ecosystems are defined by the network of interactions between organisms, as well as between organisms and their environment. The boundaries of an ecosystem are chosen for practical reasons related to the objectives of a particular study. For example, a safe transportation ecosystem of mainline infrastructure includes as a biological component both the passenger flow and service personnel and the biosphere surrounding them. Progress toward eliminating humans from the management of a fully automated vehicle will increasingly emphasize the role of the vehicle and the environment, including the track and other infrastructure. The latter generally refers to technological, organizational, and logistical components whose development requires significant innovation, including in such key areas as microelectronics and power supply. Solar cells consist of layers that absorb sunlight and convert it into electric current. Let us note the significant progress in such a practically important direction as flexible electronics based on filamentous nanocrystals (NNCs) achieved in recent years [1][2][3]. Due to their mechanical properties (elasticity, flexibility), NOC films can withstand significant deformations, which allows their use in flexible optoelectronic devices. Various flexible NNK-based devices, such as photodetectors and solar cells, have already been demonstrated. Various methods of creating flexible structures based on NOCs have been developed [4,5]. One of the methods of creating a flexible structure with preservation of the initial vertical orientation of NOCs is polymer deposition onto an array of NOCs grown on a substrate, followed by mechanical separation of the outcomesing film from the substrate.
Earlier in [6,7], we showed the possibility of growing practically 100% coherent InP/InAsP/InP NOCs concerning the silicon substrate. In [3,7] it was found that the application of the TOPO layer containing CdSe/ZnS colloidal dots (QD) to the array consisting of InP/InAsP/InP hybrid nanostructure NNCs. leads to a significant increase in the duration and intensity of InAsP nano wave (NV) luminescence. After a certain dwell time, the colloid polymerizes, forming a film that can be easily separated from the substrate ( The short-wave band of 1.1-1.2 μm is associated with the radial quantum well (QW) formed when a thin layer of InAsP is deposited on the NNP surface during InAsP NV growth.
The present paper provides the outcomess of processing the obtained experimental PL attenuation kinetics (Fig. 3) of a hybrid InP/InAsP/InP NNC nanostructure passivated by a TORO-QD CdSe/ZnS layer based on several model representations.
Recall that in semiconductor QDs, the energy gap between the energy levels of spatial quantization is markedly larger than the energy of optical phonons, so the return of the electron to the lower excited state 1 occurs in two ways: energy levels of dimensional quantization and "phonon-free" relaxation through trapped levels [6]. The presence of the colloidal shell leads to an increase in the duration of the first and the appearance of the second component of luminescence in NV. In [3,7,16] the kinetics of PL QW and QW InAsP luminescence attenuation at 80 and 295 K were measured in the absence and presence of colloidal shell QD CdSe/ZnS. Table 1 shows the outcomess of the PL kinetic measurements of QW and QI carried out in the work. The faster component (τ1) corresponds to the direct excitation of InAsP nanowalls, and the longer component (τ2) is the outcomes of passivation of the NOC surface by the colloidal shell of the TORO-CdSe/ZnS QD, leading to the appearance of hybridized states due to strong surface-ligand interactions. Such states are relatively close in energy to the fundamental radiative exciton state and can capture charge carriers with subsequent delocalization. In other words, the deposition of a TORO-QD layer on the NNP increases the luminescence intensity both through surface passivation, which increases the duration of InAsP radiation decay, and by increasing the contributions of other excitation energy exchange channels in the hybrid structure [11], including through electron-phonon and trap states in the InAsP/InP heterojunction region, diffusion of electron-hole pairs (excitons) arising from excitation of the InP NOC shell, and processes at the NOC-TORO-QD interface. The recharge of the NV emitting state arising in the presence of the colloidal shell may also be related to the backward transfer of excitation from the traps close to the NV, populated during the relaxation of highly excited states. These processes contribute to an increase in the occupancy of the lower excited state 1. The appearance of biexponential kinetics and enhancement of luminescence. The long PL decay times of InAsP NV (Table 2), atypical for radiative recombination in directgap semiconductors, are noteworthy.
Tables 3 and 4 present the PL attenuation kinetics parameters obtained taking into account the return of excitation from the traps [17].

Reverse Transfer
For NVs, as was shown in [13], the main quenching mechanism is the so-called "contact quenching" [17,18], associated with the formation of traps near the NV NOCs as an outcome of deformations caused by a second-order phase transition. It is reasonable to assume that the increase in the luminescence intensity is associated with an increase in the probability of excitation transfer from QW to NV caused by textural rearrangements during ligand sheath formation. This excitation retranslation channel can be greatly enhanced by the backward transfer. The model that is proposed to describe PL decays in InP/InAsP/InP NVs is as follows. The InP/InAsP/InP NV at room temperature is considered a two-level system including a non-emitting dark state (accumulating trap-capture processes) and an excited emitting (bright) state (PL). The bright state decays radiative at an average rate of 1/τ. We assume that the charges potentially photogenerated in InP NOCs (including NVs) can be captured by N identical electron (or hole) traps with a finite average electron (or hole) capture rate constant, k1. In this case, the morphology of the traps may be different. The assumption of an average rate constant for charge capture is made to limit the number of free parameters in the model. A trapped electron (or hole) (its backstory is not taken into account) can be transferred back to the NV with a rate constant of k2 (k1>k2). We also assume that the decay rate of the trap state 1/τtrap is negligible compared to k2, that is, 1/τtrap≪k2. One can check the existence of FRET transport in the system under study using the so-called "stretched exponent" [12]: Where τ is the lifetime of the excited state of NV luminescent QD, 0 < b ≤ 1, and depends on the luminescence quenching mechanism, a is a constant that depends on the concentration of quenching molecules. The existence of the transfer should lead to the appearance among the components of the excited state decay of the component corresponding to the FRET mechanism. The solution of the corresponding kinetic equations gives the following description formula for the luminescence attenuation kinetics of NV with allowance for additional excitation through the QD of CdSe/ZnS [13,19]: τQW is the luminescence decay time of QD CdSe/ZnS, τ is the lifetime of NV, k is the rate constant of energy transfer from QD CdSe/ZnS to NV, B is the parameter characterizing the excitation degree of QD CdSe/ZnS at the initial time. The fitting parameters in this model are τQW, τ, k, and B.
Thus, the photodynamics of "reverse transport" consists of two stages: the rapid accumulation of excitation on traps of different types and the time-spanning release of carriers and their radiative recombination.

Conclusion
The kinetics of PL heterostructure attenuation representing isolated films of QDs CdSe/ZnS-TOPO containing InP/InAsP/InP nanowires is considered from the position of the evolution of conceptual notions linking different interdisciplinary ecosystem fragments. The outcomess of electrokinetic studies show that the deposition of a TORO-QD layer on NNCs increases the luminescence intensity both by passivation of the surface and by increasing the contribution of the excitation backward transfer process from traps to emitting centers, which increases the duration of the radiation decay of InAsP NVs. Another reason for the long relaxation times is the emergence of a heterojunction of the second kind at the boundary between the InAsP NV and the InP volume. A model of the process kinetics is proposed that takes into account the role of back transfer of excitation from the traps to the emitting state. The studies performed in this work suggest practical ways to increase the luminescence yield using "interfacial technologies" in core-shell structures.