Thiazole‐Modified C₃N₄ Interfacial Layer for Defect Passivation and Charge Transport Promotion in Perovskite Solar Cells

Abstract

Despite the conspicuous achievements in perovskite solar cells (PSCs), further improvement of the power conversion efficiency (PCE) is hindered by substantially detrimental carrier recombination resulting from the high interfacial charge defect density and inferior charge transport kinetics. Herein, an interface engineering strategy is developed to introduce a Lewis base thiophene or thiazole–modified C3N4 layer at the electron transfer layer (ETL)/perovskite interface to constitute a stepwise energy band alignment and passivate defects at interfaces of the perovskite film. Attributed to its well‐matched energy level with TiO2 and perovskite, the charge extraction efficiency and charge transfer dynamics can be promoted remarkably, greatly inhibiting charge recombination at the interface. Furthermore, thiophene and thiazole can donate the lone pair electrons in S or N atoms to undercoordinated Pb2+, which effectively passivates the electronic trap states caused by halogen vacancies, thereby greatly minimizing trap‐assisted nonradiative recombination in the PSCs. Eventually, the thiazole–C3N4/perovskite‐based devices acquire an outstanding efficiency of 19.23%, supported by an enhanced open‐circuit voltage (VOC) of 1.11 V with improved moisture stability. This work provides an avenue for interfacial energy level modulation and defect passivation strategies for a rational interface microstructure design for meliorating the performance of PSCs.

Dual-layer synergetic optimization of high-efficiency planar perovskite solar cells using nitrogen-rich nitrogen carbide as an additive

“…Generally, for ideal devices without an interface barrier or carrier imbalance, the corresponding slope index will approach 1. 25,27 More specifically, the slope of the A2 device (0.98) is closer to the ideal value compared with the control (0.89) and A1 devices (0.95), indicating inhibited bimolecular recombination and boosted charge extraction. Fig.…”

“…The linear plots are fitted according to the following formula: V oc = n ( k B T / q ) ln( I ′) + a , where n is the ideal factor, k B is the Boltzmann constant, T is the temperature, q is the elementary charge, I ′ is the light intensity and a is a constant. 25 The reduced ideal factor in the A2 device is indicative of an inhibited trap-assisted recombination procedure. The dark J–V curves were also obtained to determine the diode characteristics of the device, as shown in Fig.…”

“…24 Wang et al optimized an ETL/perovskite interface by using thiazole modified g-C 3 N 4 to achieve significant enhancement of PCEs. 25 Chen et al designed and fabricated SnO 2 /g-C 3 N 4 quantum dot composites as functional electron transport layers to obtain efficient and stable photovoltaic devices. 26 Interestingly, due to the transition between the weak local π–π* states of sp 2 hybridization of C and N, nitrogen-rich graphitic nitride (g-C 3 N 5 ) obtained by introducing triazole units into the triazine network has a smaller optical band gap (about 2.2 eV) than g-C 3 N 4 (about 2.7 eV), which means that g-C 3 N 5 has stronger visible light absorption ability.…”

Impact of Alkyl Chain Length on the Properties of Fluorenyl-Based Linear Hole-Transport Materials in p-i-n Perovskites Solar Cells

“…The gain size of perovskites grown on FMT-D ( D ave = 410 nm) was larger than the ones on ITO ( D ave = 280 nm), FMT-M ( D ave = 180 nm), and FMT ( D ave = 300 nm). The increasing crystal grain size benefits the high-performance devices, because the edge of the grain boundary is considered a defect that can cause direct recombination of carriers. − …”

Carbon Quantum Dot-Passivated Perovskite/Carbon Electrodes for Stable Solar Cells

“…To date, the best-performing PSC has reached up to 25.5% power conversion efficiency (PCE), far beyond that of the DSSCs. − Light-harvesting materials of organic–inorganic methylammonium lead halide perovskite, presenting excellent optical and electronic properties, have attracted widespread attention for the past decade. − Although great achievements have been made for PSCs to compete with the other types of solar cells in recent years, challenges of further enhancing the photovoltaic performance and long-term stability of PSCs still exist. , In particular, how to achieve good perovskite films with few defects is in the forefront. Due to the migration of methylamine and iodine ions, organic halide perovskites are prone to form a large number of defects on the surface and grain boundaries, and these defects cause carrier recombination and reduce the performance of PSCs. , Passivating grain boundaries and surface defects of perovskite film is essential for fabricating high-performance PSCs. − Unreacted Pb 2+ and halogen ions can be coordinated via chemically reacting with passivation agents; thus, good perovskite films with less defect states can be attained.…”