How to Reduce Charge Recombination in Organic Solar Cells: There are Still Lessons to Learn from P3HT:PCBM

Abstract

However, despite the wide variety of materials that are now available, there are still only a few systems that maintain their full performance at junction thicknesses of 300 nm and more. [4][5][6] Compatibility with thick active layers, as well as a general tolerance to thickness variations, is considered an important prerequisite for the low-cost production of OPVs using printing techniques. [7,8] The main problem with increasing thickness is the slowdown of charge collection, which makes photogenerated carriers more vulnerable to recombination. [9][10][11] This is particularly true for NFA-based systems, which typically have low carrier mobilities of 10 −9 to 10 −8 m 2 V −1 s −1

Cross-Linking of Doped Organic Semiconductor Interlayers for Organic Solar Cells: Potential and Challenges

“…Notably, the P3HT:PCBM blend layer was prepared in a manner that leads to an exceptionally low bimolecular recombination coefficient of k 2 ∼ 10 –19 m 3 s –1 in the bulk. 41 This enabled us to study devices with a relatively large absorber thickness of 300 nm without notable transport losses. Such thick layers are considered not only an important prerequisite for low-cost fabrication using printing techniques 42 , 43 but also particularly susceptible to space charge effects and therefore ideally suited to investigate the impact of a possible diffusion of dopants from the HTL into the active layer.…”

“…Table 2 lists the key input parameters of the model. The values related to the P3HT:PCBM blend layer were taken from a recent study 41 in which the same processing protocol was used as in this work. The nonuniform generation rate profile of the thick-film devices was fully taken into account by coupling the drift–diffusion simulator with the transfer-matrix model.…”

Enhanced efficiency in hollow core electrospun nanofiber-based organic solar cells

“…The resulting solution was spin-coated onto the buffer layer's surface with a rotation of 1500 rpm for 4 min. The sample was then placed on a hot plate at 70 °C for 10 min 28 .…”

Quantifying the optimal thickness in polymer:fullerene solar cells from the analysis of charge transport dynamics and photoabsorption

“…S12 and Table S2 †) reveal the L opt values of 180-300 nm for P3HT:PCBM (DCB) and 60-110 nm for P3HT:PCBM (CB), which are consistent with those of literature reports (180-320 nm and 65-100 nm, respectively). 69 The spincoated and drop-cast lms (DCB) show similar morphology (AFM and XRD in ESI Fig. S13 †); thus, solvent rather than the lm thickness and casting methods has a marked effect on L opt .…”

“…To examine the applicability of L opt determination to the different processes for the identical material, we prepared P3HT:PCBM BHJs from either CB or DCB solution (ESI Note S6 †) according to the same process as that described in ref. 69 The TOF-TRMC experiments (ESI Fig. S10 and S11 †) and their analyses (ESI Fig.…”