Charge Carrier Generation and Extraction in Hybrid Polymer/Quantum Dot Solar Cells

Abstract

Here we investigate charge carrier generation and extraction processes in hybrid polymer/nanocrystal solar cells by means of time-resolved optical and photoelectrical techniques. We addressed the role of both poly(3-hexylthiophene) and colloidal arenethiolate-capped PbS quantum dots, which constitute the hybrid composite nanomaterial, in the photoinduced processes most relevant to device operation by changing the compositional ratio and applying chemical and thermal postdeposition treatments. The carrier generation processes were found to be wavelength-dependent: excitons generated in the polymer domains led to long-lived weakly bound charge pairs upon electron transfer to PbS nanocrystals; whereas charge carrier generation in the nanocrystal domains is highly efficient, although effective separation required the application of external electric field. Overall, charge carrier generation was found efficient and almost independent of the strength of applied electric field; therefore, competition between separation of electron−hole pairs into free carriers and geminate recombination is the major factor limiting the fill factor of nanocomposite-based solar cells. Device efficiency improvements thus require faster interfacial charge transfer processes, which are deeply related to the refinement of nanocrystal surface chemistry.

Imaging the Anomalous Charge Distribution Inside CsPbBr3 Perovskite Quantum Dots Sensitized Solar Cells

“…In a high-performance perovskite solar cell, the charge transport dynamics depend on the perfect band alignment across the layers of the perovskite absorber, electron transport layer (ETL), and hole transport layer (HTL), which makes it easy to separate the photoinduced charge carriers and transport them to the respective electrodes. Efficient charge transfer process also depends on the generation and extraction of the charge carriers at the interfaces. − …”

Toward efficient hybrid solar cells comprising quantum dots and organic materials: progress, strategies, and perspectives

“…[143][144][145] With the deepening of the understanding on carrier transport of hybrid heterojunction, fast electron and hole transports were conrmed between polymers and QDs with short ligands. [146][147][148][149][150] Beneting from continuous efforts, the performance of hybrid QD:organic solar cells has witnessed rapid progress within a few years. Due to the simple synthesis and low cost, P3HT has proved to be the early popular polymer with QDs; however, it presents a moderate PCE, mainly due to the absorption mismatch of the two materials and the driving lack from the low energy landscape difference.…”

Polymer/quantum dot nanostructures in remarkably stabilized photovoltaics based on polymers having benzodithiophene/naphthothiadiazole constituents

“…[10][11][12][13][14][15][16][17][18][19][20][21] In this regard, the polymer/quantum dot (QD) compositions have retained attention for the morphological and structural manipulations in photovoltaics. [22][23][24][25][26][27][28][29][30] For having the proper carrier generation, cheapness, and optical activities depending on size, the 2 | EXPERIMENTAL CQD preparation. Citric acid and ethylenediamine were dissolved in water and reached 195 C and kept at this temperature for 15 hours and finally cooled to the room temperature.…”