Charge transport in quantum dot organic solar cells with Si quantum dots sandwiched between poly(3-hexylthiophene) (P3HT) absorber and bathocuproine (BCP) transport layers

Abstract

We have modeled a multilayer quantum dot organic solar cell that explores the current-voltage characteristic of the solar cell whose characteristics can be tuned by varying the fabrication parameters of the quantum dots (QDs). The modeled device consists of a hole transport layer (HTL) which doubles up as photon absorbing layer, several quantum dot layers, and an electron transport layer (ETL). The conduction of charge carriers in HTL and ETL has been modeled by the drift-diffusion transport mechanism. The conduction and recombination in the quantum dot layers are described by a system of coupled rate equations incorporating tunneling and bimolecular recombination. Analysis of QD-solar cells shows improved device performance compared to the similar bilayer and trilayer device structures without QDs. Keeping other design parameters constant, solar cell characteristics can be controlled by the quantum dot layers. Bimolecular recombination coefficient of quantum dots is a prime factor which controls the open circuit voltage (VOC) without any significant reduction in short circuit current (JSC).

Electronic and Excitonic Processes in Quantum Dot Light-Emitting Diodes

“…Therefore, we deduce that the outstanding performance of ZnO-based devices must be closely related to the type of AR and/or carrier-injection sequence. In the previous reports, charge injection from the transport layer to QDs and transport between QDs were considered as charge-capturing and direct-tunneling processes, respectively. − Jung et al simulated the photoelectrical properties of QLEDs using the typical Langevin recombination, where the Auger capture probabilities of both holes and electrons were considered to be the same. Actually, the capture processes for the holes and electrons should be distinct for the QLEDs given that the electron and hole are injected into a QD sequentially. ,, In particular, the AR processes of eeh and ehh should play a different role in determining the device performance.…”

Optoelectronic system and device integration for quantum-dot light-emitting diode white lighting with computational design framework

“…The simulation model uses continuity equations as the governing equations for the calculation of dynamic behaviours of holes and electrons and Poisson’s equation for solving the electrostatic potential across the QD-LED device 27 , 28 , 30 , 35 , 56 . As a numerical technique for solving the second-order partial differential equations of the continuity equations combined with Poisson’s equation, we used the finite difference method (FDM) on a discretised grid space across the QD-LED device 57 .…”

“…However, the problem of optimising the light emission architecture of a white lighting system remains unresolved, as it requires an excessive amount of colour calculations for the massive combinations of QD colours and their geometrical combinations available for pixel layout. To reduce the number of colour evaluations for the optimal layout design, one of the systematic and efficient approaches is to employ computational design by way of combinatorial colour optimisation and accurate charge transport simulation of QD-LED devices [27][28][29][30] .…”

Computational Characterization of Quantum‐Dot Light‐Emitting Diodes by Combinatorial Exciton Recombination Parameters and Photon Extraction Efficiency

“…To analyze the voltage-dependent EQE of the QD-LED devices effectively, a computational charge transport model has been proposed, which enables simulation of the dynamic motion of the electron and hole charge carriers across QD-LED devices. [26][27][28][29][30][31] However, to make accurate predictions of the voltage-dependent electro-optical properties of the QD-LED and ensure the reliable functionality of AM displays, it remains essential to obtain both the exact ABC parameters and the photon extraction efficiency of QD-LED devices, simultaneously.…”